Infusion pressure and pain during microneedle injection into skin of human subjects.
Gupta Jyoti,Park Sohyun S,Bondy Brian,Felner Eric I,Prausnitz Mark R
Infusion into skin using hollow microneedles offers an attractive alternative to hypodermic needle injections. However, the fluid mechanics and pain associated with injection into skin using a microneedle have not been studied in detail before. Here, we report on the effect of microneedle insertion depth into skin, partial needle retraction, fluid infusion flow rate and the co-administration of hyaluronidase on infusion pressure during microneedle-based saline infusion, as well as on associated pain in human subjects. Infusion of up to a few hundred microliters of fluid required pressures of a few hundred mmHg, caused little to no pain, and showed weak dependence on infusion parameters. Infusion of larger volumes up to 1 mL required pressures up to a few thousand mmHg, but still usually caused little pain. In general, injection of larger volumes of fluid required larger pressures and application of larger pressures caused more pain, although other experimental parameters also played a significant role. Among the intradermal microneedle groups, microneedle length had little effect; microneedle retraction lowered infusion pressure but increased pain; lower flow rate reduced infusion pressure and kept pain low; and use of hyaluronidase also lowered infusion pressure and kept pain low. We conclude that microneedles offer a simple method to infuse fluid into the skin that can be carried out with little to no pain.
Trapping cells on a stretchable microwell array for single-cell analysis.
Wang Yuli,Shah Pavak,Phillips Colleen,Sims Christopher E,Allbritton Nancy L
Analytical and bioanalytical chemistry
There is a need for a technology that can be incorporated into routine laboratory procedures to obtain a continuous, quantitative, fluorescence-based measurement of the dynamic behaviors of numerous individual living cells in parallel, while allowing other manipulations, such as staining, rinsing, and even retrieval of targeted cells. Here, we report a simple, low-cost microarray platform that can trap cells for dynamic single-cell analysis of mammalian cells. The elasticity of polydimethylsiloxane (PDMS) was utilized to trap tens of thousands of cells on an array. The PDMS microwell array was stretched by a tube through which cells were loaded on the array. Cells were trapped on the array by removal of the tube and relaxation of the PDMS. Once that was accomplished, the cells remained trapped on the array without continuous application of an external force and permitted subsequent manipulations, such as staining, rinsing, imaging, and even isolation of targeted cells. We demonstrate the utility of this platform by multicolor analysis of trapped cells and monitoring in individual cells real-time calcium flux after exposure to the calcium ionophore ionomycin. Additionally, a proof of concept for target cell isolation was demonstrated by using a microneedle to locally deform the PDMS membrane in order to retrieve a particular cell from the array.
New Approach for Near-Real-Time Measurement of Elemental Composition of Aerosol Using Laser-Induced Breakdown Spectroscopy.
Diwakar Prasoon,Kulkarni Pramod,Birch M Eileen
Aerosol science and technology : the journal of the American Association for Aerosol Research
A new approach has been developed for making near-real-time measurement of elemental composition of aerosols using plasma spectroscopy. The method allows preconcentration of miniscule particle mass (pg to ng) directly from the sampled aerosol stream through electrostatic deposition of charged particles (30-900 nm) onto a flat-tip microneedle electrode. The collected material is subsequently ablated from the electrode and monitored by laser-induced breakdown spectroscopy. Atomic emission spectra were collected using a broadband spectrometer with a wavelength range of 200-980 nm. A single-sensor delay time of 1.3 s was used in the spectrometer for all elements to allow simultaneous measurement of multiple elements. The system was calibrated for various elements including Cd, Cr, Cu, Mn, Na, and Ti. The absolute mass detection limits for these elements were experimentally determined and found to be in the range of 0.018-5 ng. The electrostatic collection technique has many advantages over other substrate-based methods involving aerosol collection on a filter or its focused deposition using an aerodynamic lens. Because the particle mass is collected over a very small area that is smaller than the spatial extent of the laser-induced plasma, the entire mass is available for analysis. This considerably improves reliability of the calibration and enhances measurement accuracy and precision. Further, the aerosol collection technique involves very low pressure drop, thereby allowing higher sample flow rates with much smaller pumps-a desirable feature for portable instrumentation. Higher flow rates also make it feasible to measure trace element concentrations at part per trillion levels. Detection limits in the range of 18-670 ng m can be achieved for most of the elements studied at a flow rate of 1.5 L min with sampling times of 5 min.
[A challenge to primary open-angle glaucoma including normal-pressure. Clinical problems and their scientific solution].
Nippon Ganka Gakkai zasshi
Primary open-angle glaucoma (POAG), including normal-tension glaucoma (NTG), is reported by the Tajimi Study to afflict 3.9% of the total population, and this represents about 80% of all total glaucoma cases which, in total, afflict 5.0% of the population. We tried to analyze the clinical problems relating to POAG by looking at the pathogenesis, intraocular pressure (IOP), therapy, neuroprotection and surgery of the disease. To elucidate the pathogenesis of glaucoma progression, we measured retinal nerve fiber layer defect (RNFLD) angles', and divided the NTG cases into 2 groups, enlarged RNFLD and stable RNFLD. Disc hemorrhages were found to be significantly more frequent in the enlarged group than in the stable group. RNFLD was enlarged in the direction of disc hemorrhage in over 80% of the eyes. In the majority of the eyes of the enlarged group, the enlargement of RNFLD was toward the fovea. The enlargement of RNFLD in NTG was closely associated with disc hemorrhage and the deterioration of the visual field. We developed a simultaneous structure and function evaluation technique combining spectral-domain (SD) optical coherence tomography (OCT) and fundus-oriented perimeters for the detection of visual field abnormalities in the RNFLD area. We superimposed the ganglion cell complex map obtained by SD-OCT on the fundus-oriented perimeter image. We observed very early or preperimetric normal pressure glaucoma as well as disc hemorrhage adjacent to the borders of the RNFLD. The borderline of the RNFLD seemed to be the thinnest RNFL and had the lowest retinal sensitivity (Active site for RNFLD progression). To clarify the role of the circadian clock genes in the generation of a 24-hour IOP rhythm, we used the microneedle method to measure the IOP at eight time points daily, both in wild type mice and Cry-deficient (Cry 1-/-Cry 2-/-) mice. In the wild-type mice living in light-dark conditions, the pressure measured in the light phase was significantly lower than in the dark phase. This biphasic daily rhythm was maintained under dark-dark conditions. In contrast, the Cry-deficient mice did not show significant circadian changes in their IOP, regardless of the environmental light conditions. These findings demonstrate that clock genes are essential for the generation of the circadian rhythm of IOP. We evaluated the relationship between the genetic polymorphisms of the adrenergic receptor (ADR) and the diurnal IOP in untreated NTG patients. For Del 301-303 in α2B-ADR, De1322-325 in α2C-ADR, and S 49G (A/G) in βl-ADR, the major homozygotes and minor carriers had parallel diurnal IOP curves, but significantly different diurnal IOP levels. Polymorphisms of the ADR gene may predict the diurnal IOP level of patients with NTG. Looking toward the future, tailor-made medicine in glaucoma therapy, we evaluated the relationship between the polymorphisms of the prostaglandin F2α, receptor (FP receptor) gene and the effectiveness of topical latanoprost treatment in 100 normal volunteers. One SNP(rs3753380) was located in the promoter region of the FP receptor gene and was significantly correlated with % IOP reduction. Two SNPs, rs3753380 and rs3766355 (an SNP in intron 1), were associated with the degree of response to latanoprost. The genotype of these SNPs may be an important determinant of variability in response to latanoprost. To investigate the predictability of IOP response of the fellow eye in a one-eye trials, we compared the correlation of the fellow-eye's IOP response in one-eye trials performed separately for each eye with that of bilateral treatment in 41 normal subjects. Correlation of mean diurnal IOP reduction between 2 one-eye trials was poor (r2 = 0.102), even after subtracting the nontreated eye IOP fluctuations from the treated eye IOPs (r2 = 0.097), but that between fellow eyes in bilateral treatment was excellent (r2 = 0.849). Therefore, we examined the effects of multiple IOP measurements on the correlation of response to glaucoma medication between fellow eyes. Latanoprost was applied to the first eye and then to both eyes of POAG or ocular hypertension patients. IOP measurements were performed twice on different days at baseline, during treatment of the first eye only and for both eyes. No significant correlations of ΔIOP 1 (IOP at baseline-IOP after treatment) between fellow eyes were found. ΔIOP 2 (ΔIOP 1-IOP fluctuation of the contralateral eye) was significantly correlated between the fellow eyes using two post-treatment IOP measurements. Using multiple IOP measurements may improve the prediction of a fellow eye's response to glaucoma medication in one-eye trials. We used a scanning laser ophthalmoscope (SLO) for in vivo imaging and counting of rat retinal ganglion cells (RGCs). RGC survival decreased gradually after crushing the optic nerve. RGC counts by SLO were comparable to those in retinal flat mounts. We developed OCT system for rat eyes. The mean retinal nerve fiber layer (RNFL) thicknesses in the circumpapillary OCT scans were unchanged 1 week after crushing the optic nerve, but then decreased significantly and progressively after the second week. RNFL thicknesses in OCT images correlated significantly with thicknesses determined histologically. SLO and OCT will be useful for evaluating the effects of neuroprotective drugs. We developed a new glaucoma filtration surgery system using a thin honeycomb-patterned biodegradable film in rabbits. The film had a honeycomb-patterned surface that faced the subconjunctival Tenon tissue, while the other side was smooth. Postoperative IOPs of the film-treated eyes were significantly lower than those of the control eyes, but were not significantly different from those of the MMC-treated eyes. The thin honeycomb-patterned film that was attached to the inner bleb wall worked as an adhesion barrier in glaucoma filtration surgery in rabbits.
In vivo interactions between tungsten microneedles and peripheral nerves.
Sergi Pier Nicola,Jensen Winnie,Micera Silvestro,Yoshida Ken
Medical engineering & physics
Tungsten microneedles are currently used to insert neural electrodes into living peripheral nerves. However, the biomechanics underlying these procedures is not yet well characterized. For this reason, the aim of this work was to model the interactions between these microneedles and living peripheral nerves. A simple mathematical framework was especially provided to model both compression of the external layer of the nerve (epineurium) and the interactions resulting from penetration of the main shaft of the microneedle inside the living nerves. The instantaneous Young's modulus, compression force, the work needed to pierce the tissue, puncturing pressure, and the dynamic friction coefficient between the tungsten microneedles and living nerves were quantified starting from acute experiments, aiming to reproduce the physical environment of real implantations. Indeed, a better knowledge of the interactions between microneedles and peripheral nerves may be useful to improve the effectiveness of these insertion techniques, and could represent a key factor for designing robot-assisted procedures tailored for peripheral nerve insertion.
Recent overview of ocular patents.
Gaudana Ripal J,Gokulgandhi Mitan R,Boddu Sai H S,Mitra Ashim K
Recent patents on drug delivery & formulation
Ocular drug therapy has always been considered as a major challenge in the field of drug delivery. The presence of blood ocular barriers and efflux pumps has imposed a great concern as well. Various vision threatening disorders require a long term therapy of drug molecules, especially for the diseases that affect the posterior segment. Pharmaceutical companies and other research institutes have adopted a multidisciplinary approach to meet the current challenges which is evidenced by the trends seen in the published and filed U.S. patents. Various strategies have been employed to achieve long term sustained and targeted delivery for both the anterior and the posterior segments of the ocular diseases. These strategies include formulating drugs into implant, micro or nanoparticulate systems and hydrogel-based systems. Transporter targeted approach has also allowed scientists to deliver drugs to both the segments of the eye. Recent developments such as delivery of drugs utilizing ultrasound, iontophoresis and microneedle based devices have been promising. Genebased therapeutics has opened a new avenue for vision threatening disorders. In all, the current developments in the entire field have been very exciting for finding out new strategies to treat vision threatening disorders.
Polycaprolactone scaffold as targeted drug delivery system and cell attachment scaffold for postsurgical care of limb salvage.
Wong Bin Sheng,Teoh Swee-Hin,Kang Lifeng
Drug delivery and translational research
In this paper, a dual-function drug-laden polycaprolactone scaffold, which can serve as both targeted drug delivery system and attachment platform for tissue regeneration for the postsurgical care of limb salvage procedure, was developed with a simple and solvent-free molding technique. Scaffolds of varying surface architecture were created using poly(ethylene glycol) diacrylate microneedle arrays. A model drug, rhodamine B, was incorporated homogenously into the scaffold. In vitro drug release studies showed that rhodamine B was released in a slow and sustained manner for 112 days. Its release rate was affected by drug loading and scaffold surface architecture. Release of rhodamine B from the scaffolds followed the Higuchi diffusion model. Other drugs, namely, doxorubicin and lidocaine hydrochloride, were also effectively loaded into and released from the scaffolds. Cell attachment study demonstrated potential for the scaffolds to provide attachment platforms for tissue regeneration.
Splicing variant of AIMP2 as an effective target against chemoresistant ovarian cancer.
Choi Jin Woo,Lee Jeong-Won,Kim Jun Ki,Jeon Hye-Kyung,Choi Jung-Joo,Kim Dae Gyu,Kim Byoung-Gie,Nam Do-Hyun,Kim Hong Joong,Yun Seok Hyun,Kim Sunghoon
Journal of molecular cell biology
Chemoresistance is a main cause for the failure of cancer management and intensive investigation is on-going to control chemoresistant (CR) cancers. Although NF-κB has been suggested as one of the potential targets to alleviate chemoresistance of epithelial ovarian cancer (EOC), direct targeting of NF-κB may result in an unexpected effect due to the complex regulatory network via NF-κB. Here we show that AIMP2-DX2, a splicing variant of tumor suppressor AIMP2, can be a therapeutic target to control CR EOC. AIMP2-DX2 was often highly expressed in CR EOC both in vitro and in vivo. AIMP2-DX2 compromised the tumor necrosis factor alpha-dependent pro-apoptotic activity of AIMP2 via the competitive inhibition of AIMP2 binding to TRAF2 that plays a pivotal role in the regulation of NF-κB. The direct delivery of siRNA against AIMP2-DX2 into abdominal metastatic tumors of ovarian cancer using a microneedle converged on microendoscopy significantly suppressed the growth rate of tumors. The treated cancer tissues showed an enhanced apoptosis and the decreased TRAF2 level. Thus, we suggest that the downregulation of AIMP2-DX2 can be a potent adjuvant therapeutic approach for CR EOC that resulted from an aberrant activity of NF-κB.
A minimally invasive system for glucose area under the curve measurement using interstitial fluid extraction technology: evaluation of the accuracy and usefulness with oral glucose tolerance tests in subjects with and without diabetes.
Sakaguchi Kazuhiko,Hirota Yushi,Hashimoto Naoko,Ogawa Wataru,Sato Toshiyuki,Okada Seiki,Hagino Kei,Asakura Yoshihiro,Kikkawa Yasuo,Kojima Junko,Maekawa Yasunori,Nakajima Hiromu
Diabetes technology & therapeutics
BACKGROUND:Recent studies have highlighted the importance of managing postprandial hyperglycemia, but adequate monitoring of postprandial glucose remains difficult because of wide variations in levels. We have therefore developed a minimally invasive system to monitor postprandial glucose area under the curve (AUC). This system involves no blood sampling and uses interstitial fluid glucose (IG) AUC (IG-AUC) as a surrogate marker of postprandial glucose. This study aimed to evaluate the usefulness of this system by comparing data with the findings of oral glucose tolerance tests (OGTTs) in subjects with and without diabetes. SUBJECTS AND METHODS:The glucose AUC monitoring system was validated by OGTTs in 37 subjects with and 10 subjects without diabetes. A plastic microneedle array was stamped on the forearm to extract IG. A hydrogel patch was then placed on the pretreated area to accumulate IG. Glucose and sodium ion concentrations in the hydrogel were measured to calculate IG-AUC at 2-h postload glucose. Plasma glucose (PG) levels were measured every 30 min to calculate reference PG-AUC. RESULTS:IG-AUC correlated strongly with reference PG-AUC (r=0.93) over a wide range. The level of correlation between IG-AUC and maximum PG level was also high (r=0.86). The painless nature of the technique was confirmed by the response of patients to questionnaires. CONCLUSIONS:The glucose AUC monitoring system using IG provided good estimates of reference PG-AUC and maximum PG level during OGTTs in subjects with and without diabetes. This system provides easy-to-use monitoring of glucose AUC, which is a good indicator of postprandial glucose.
DNA vaccination in the skin using microneedles improves protection against influenza.
Song Jae-Min,Kim Yeu-Chun,O Eunju,Compans Richard W,Prausnitz Mark R,Kang Sang-Moo
Molecular therapy : the journal of the American Society of Gene Therapy
In this study, we tested the hypothesis that DNA vaccination in the skin using microneedles improves protective immunity compared to conventional intramuscular (i.m.) injection of a plasmid DNA vaccine encoding the influenza hemagglutinin (HA). In vivo fluorescence imaging demonstrated the expression of a reporter gene delivered to the skin using a solid microneedle patch coated with plasmid DNA. Vaccination at a low dose (3 µg HA DNA) using microneedles generated significantly stronger humoral immune responses and better protective responses post-challenge compared to i.m. vaccination at either low or high (10 µg HA DNA) dose. Vaccination using microneedles at a high (10 µg) dose further generated improved post-challenge protection, as measured by survival, recall antibody-secreting cell responses in spleen and bone marrow, and interferon (IFN)-γ cytokine T-cell responses. This study demonstrates that DNA vaccination in the skin using microneedles induces higher humoral and cellular immune responses as well as improves protective immunity compared to conventional i.m. injection of HA DNA vaccine.
A minimally invasive microchip for transdermal injection/sampling applications.
Strambini Lucanos M,Longo Angela,Diligenti Alessandro,Barillaro Giuseppe
Lab on a chip
The design, fabrication, and characterization of a minimally invasive silicon microchip for transdermal injection/sampling applications are reported and discussed. The microchip exploits an array of silicon-dioxide hollow microneedles with density of one million needles cm(-2) and lateral size of a few micrometers, protruding from the front-side chip surface for one hundred micrometers, to inject/draw fluids into/from the skin. The microneedles are in connection with independent reservoirs grooved on the back-side of the chip. Insertion experiments of the microchip in skin-like polymers (agarose hydrogels with concentrations of 2% and 4% wt) demonstrate that the microneedles successfully withstand penetration without breaking, despite their high density and small size, according to theoretical predictions. Operation of the microchip with different liquids of biomedical interest (deionized water, NaCl solution, and d-glucose solution) at different differential pressures, in the range 10-100 kPa, highlights that the flow-rate through the microneedles is linearly dependent on the pressure-drop, despite the small section area (about 13 μm(2)) of the microneedle bore, and can be finely controlled from a few ml min(-1) up to tens of ml min(-1). Evaporation (at room temperature) and acceleration (up to 80 g) losses through the microneedles are also investigated to quantify the ability of the chip in storing liquids (drug to be delivered or collected fluid) in the reservoir, and result to be of the order of 70 nl min(-1) and 1300 nl min(-1), respectively, at atmospheric pressure and room temperature.
Astral microtubules physically redistribute cortical actin filaments to the incipient contractile ring.
Tseng Kuo-Fu,Foss Margit,Zhang Dahong
Cytoskeleton (Hoboken, N.J.)
Prior to cell cleavage, cytokinetic proteins are recruited into the nascent actomyosin contractile ring, paving the way for formation of a functional cleavage furrow. Interactions between spindle microtubules and the cell cortex may play a critical role in this recruitment, since microtubules have been shown to affect distribution and activation of cytokinetic proteins within the cortex. However, direct evidence for physical interaction between microtubules and the cortex has been lacking. Here, we probed the physical connection between astral microtubules and cortical actin filaments, by micromanipulating the fluorescently tagged cytoskeleton in living spermatocytes of the grasshopper Melanoplus femurrubrum. When microtubules were tugged with a microneedle, they in turn pulled on cortical actin filaments, interrupting the filaments' journey toward the equator. Further displacement of the actin dragged the cell membrane inward, demonstrating that the cortical actin network physically linked spindle microtubules to the cell membrane. Regional disruption of the connection by breaking spindle microtubules prevented actin accumulation in a segment of the ring, which locally inhibited furrowing. We propose a model in which dynamic astral microtubules physically redistribute cortical actin into the incipient contractile ring.
Polymeric microdevices for transdermal and subcutaneous drug delivery.
Ochoa Manuel,Mousoulis Charilaos,Ziaie Babak
Advanced drug delivery reviews
Low cost manufacturing of polymeric microdevices for transdermal and subcutaneous drug delivery is slated to have a major impact on next generation devices for administration of biopharmaceuticals and other emerging new formulations. These devices range in complexity from simple microneedle arrays to more complicated systems incorporating micropumps, micro-reservoirs, on-board sensors, and electronic intelligence. In this paper, we review devices currently in the market and those in the earlier stages of research and development. We also present two examples of the research in our laboratory towards using phase change liquids in polymeric structures to create disposable micropumps and the development of an elastomeric reservoir for MEMS-based transdermal drug delivery systems.
Skin cell proliferation stimulated by microneedles.
Liebl Horst,Kloth Luther C
The journal of the American College of Clinical Wound Specialists
A classical wound may be defined as a disruption of tissue integrity. Wounds, caused by trauma from accidents or surgery, that close via secondary intention rely on the biological phases of healing, i.e., hemostasis, inflammation, proliferation, and remodeling (HIPR). Depending on the wound type and severity, the inflammation phase begins immediately after injury and may last for an average of 7-14 days. Concurrent with the inflammation phase or slightly delayed, cell proliferation is stimulated followed by the activation of the remodeling (maturation) phase. The latter phase can last as long as 1 year or more, and the final healed state is represented by a scar tissue, a cross-linked collagen formation that usually aligns collagen fibers in a single direction. One may assume that skin microneedling that involves the use of dozens or as many as 200 needles that limit penetration to 1.5 mm over 1 cm(2) of skin would cause trauma and bleeding followed by the classical HIPR. However, this is not the case or at least the HIPR phases are significantly curtailed and healing never ends in a scar formation. Conversely dermabrasion used in aesthetic medicine for improving skin quality is based on "ablation" (destruction or wounding of superficial skin layers), which requires several weeks for healing that involves formation of new skin layers. Such procedures provoke an acute inflammatory response. We believe that a less intense inflammatory response occurs following microneedle perforation of the skin. However, the mechanism of action of microneedling appears to be different. Here we review the potential mechanisms by which microneedling of the skin facilitates skin repair without scarring after the treatment of superficial burns, acne, hyperpigmentation, and the non-advancing periwound skin surrounding the chronic ulcerations of the integument.
Devices for intradermal vaccination.
Kis Elsa E,Winter Gerhard,Myschik Julia
New insights in vaccine development, the need for safe, economic and efficient vaccine administration and the increasing mechanistic knowledge of immune responses induced by targeting the intradermal layers of the skin have all driven the engineering of devices for intradermal vaccination. In this review we highlight different delivery devices that make the epidermal and dermal layers of the skin accessible for vaccine administration. Depending on the device the desired vaccine can be applied either as a liquid formulation or as solid, powdered vaccine particles. The process of intradermal injection employs micron-sized needles that are inserted 1.5mm perpendicularly into the skin, and which inject approximately 100-200μl of a liquid vaccine formulation into the dermal skin layers. Tattoo devices, on the other hand, can be used to deliver liquid vaccine formulations into the dermal layer of the skin by the use of oscillating needles. Microneedle arrays are made of vaccine-coated solid microneedles or biodegradable microneedles. These are inserted into the dermal layers of the skin where either the vaccine coating is dissolved, or the microneedle itself dissolves in place. Jet-injectors operate by generating a high pressured stream, which flushes the liquid vaccine formulation into the deeper skin layers. Delivery devices using liquid vaccine formulations are advantageous, as established vaccine formulations can be used as provided without the need for reformulation. However, approaches that deliver vaccines in a solid form may also prove to be promising. One such method is the ballistic approach, in which solid vaccine particles or vaccine-coated gold particles are accelerated towards the skin by needle-free devices, so that the particles are deposited in the epidermal and dermal layers of the skin. These various delivery devices are explored in this review with regard to their delivery mechanism and ease of handling, their efficacy in clinical trials and their suitability for practical use.
Microneedles: an emerging transdermal drug delivery system.
Bariya Shital H,Gohel Mukesh C,Mehta Tejal A,Sharma Om Prakash
The Journal of pharmacy and pharmacology
OBJECTIVES:One of the thrust areas in drug delivery research is transdermal drug delivery systems (TDDS) due to their characteristic advantages over oral and parenteral drug delivery systems. Researchers have focused their attention on the use of microneedles to overcome the barrier of the stratum corneum. Microneedles deliver the drug into the epidermis without disruption of nerve endings. Recent advances in the development of microneedles are discussed in this review for the benefit of young scientists and to promote research in the area. KEY FINDINGS:Microneedles are fabricated using a microelectromechanical system employing silicon, metals, polymers or polysaccharides. Solid coated microneedles can be used to pierce the superficial skin layer followed by delivery of the drug. Advances in microneedle research led to development of dissolvable/degradable and hollow microneedles to deliver drugs at a higher dose and to engineer drug release. Iontophoresis, sonophoresis and electrophoresis can be used to modify drug delivery when used in concern with hollow microneedles. Microneedles can be used to deliver macromolecules such as insulin, growth hormones, immunobiologicals, proteins and peptides. Microneedles containing 'cosmeceuticals' are currently available to treat acne, pigmentation, scars and wrinkles, as well as for skin tone improvement. SUMMARY:Literature survey and patents filled revealed that microneedle-based drug delivery system can be explored as a potential tool for the delivery of a variety of macromolecules that are not effectively delivered by conventional transdermal techniques.
Intradermal immunization using coated microneedles containing an immunoadjuvant.
Andrianov Alexander K,Mutwiri George
A vast number of studies explore the potential of intradermal immunization, its role in the developing of new and improved vaccines and providing access to them globally. The advancement of microneedle technology offers new avenues for the practical realization of this approach, but, on certain instances, introduces new limitations and challenges in the formulation development, which involve the concern over its compatibility with existing and emerging immunoadjuvants. The present paper attempts to review various aspects of immunoadjuvant enhanced microneedle immunization and focuses on the potential of synthetic biomaterials that can play a multifunctional role in such approach. PCPP, a synthetic polyphosphazene macromolecular compound, is discussed as an example of such material that can potentially enable the technology as a microfabrication agent and a potent intradermal immunoadjuvant.
A scalable fabrication process of polymer microneedles.
Yang Sixing,Feng Yan,Zhang Lijun,Chen Nixiang,Yuan Weien,Jin Tuo
International journal of nanomedicine
While polymer microneedles may easily be fabricated by casting a solution in a mold, either centrifugation or vacuumizing is needed to pull the viscous polymer solution into the microholes of the mold. We report a novel process to fabricate polymer microneedles with a one-sided vacuum using a ceramic mold that is breathable but water impermeable. A polymer solution containing polyvinyl alcohol and polysaccharide was cast in a ceramic mold and then pulled into the microholes by a vacuum applied to the opposite side of the mold. After cross-linking and solidification through freeze-thawing, the microneedle patch was detached from the mold and transferred with a specially designed instrument for the drying process, during which the patch shrank evenly to form an array of regular and uniform needles without deformation. Moreover, the shrinkage of the patches helped to reduce the needles' size to ease microfabrication of the male mold. The dried microneedle patches were finally punched to the desired sizes to achieve various properties, including sufficient strength to penetrate skin, microneedles-absorbed water-swelling ratios, and drug-release kinetics. The results showed that the microneedles were strong enough to penetrate pigskin and that their performance was satisfactory in terms of swelling and drug release.
Delivery of subunit influenza vaccine to skin with microneedles improves immunogenicity and long-lived protection.
Koutsonanos Dimitrios G,Vassilieva Elena V,Stavropoulou Anastasia,Zarnitsyn Vladimir G,Esser E Stein,Taherbhai Misha T,Prausnitz Mark R,Compans Richard W,Skountzou Ioanna
Influenza infection represents a major socio-economic burden worldwide. Novel delivery methods can render influenza vaccination easier and more acceptable by the public, and importantly confer protection equal or superior to that induced by conventional systemic administration. An attractive target for vaccine delivery is the skin. Recent studies have demonstrated improved immune responses after transdermal delivery of inactivated influenza virus with microneedle patches. Here we show that immunization with a licensed influenza subunit vaccine coated on metal microneedles can activate both humoral and cellular arms of the immune response and confer improved long-term protection in the mouse model when compared to the conventional systemic route of delivery. These results demonstrate the promising potential of microneedle delivery of licensed influenza subunit vaccines, that could be beneficial in increasing vaccine coverage and protection and reducing influenza-related mortality worldwide.
Protein encapsulation in polymeric microneedles by photolithography.
Kochhar Jaspreet Singh,Zou Shui,Chan Sui Yung,Kang Lifeng
International journal of nanomedicine
BACKGROUND:Recent interest in biocompatible polymeric microneedles for the delivery of biomolecules has propelled considerable interest in fabrication of microneedles. It is important that the fabrication process is feasible for drug encapsulation and compatible with the stability of the drug in question. Moreover, drug encapsulation may offer the advantage of higher drug loading compared with other technologies, such as drug coating. METHODS AND RESULTS:In this study, we encapsulated a model protein drug, namely, bovine serum albumin, in polymeric microneedles by photolithography. Drug distribution within the microneedle array was found to be uniform. The encapsulated protein retained its primary, secondary, and tertiary structural characteristics. In vitro release of the encapsulated protein showed that almost all of the drug was released into phosphate buffered saline within 6 hours. The in vitro permeation profile of encapsulated bovine serum albumin through rat skin was also tested and shown to resemble the in vitro release profile, with an initial release burst followed by a slow release phase. The cytotoxicity of the microneedles without bovine serum albumin was tested in three different cell lines. High cell viabilities were observed, demonstrating the innocuous nature of the microneedles. CONCLUSION:The microneedle array can potentially serve as a useful drug carrier for proteins, peptides, and vaccines.
Effect of adjuvants on responses to skin immunization by microneedles coated with influenza subunit vaccine.
Weldon William C,Zarnitsyn Vladimir G,Esser E Stein,Taherbhai Misha T,Koutsonanos Dimitrios G,Vassilieva Elena V,Skountzou Ioanna,Prausnitz Mark R,Compans Richard W
Recent studies have demonstrated the effectiveness of vaccine delivery to the skin by vaccine-coated microneedles; however there is little information on the effects of adjuvants using this approach for vaccination. Here we investigate the use of TLR ligands as adjuvants with skin-based delivery of influenza subunit vaccine. BALB/c mice received 1 µg of monovalent H1N1 subunit vaccine alone or with 1 µg of imiquimod or poly(I:C) individually or in combination via coated microneedle patches inserted into the skin. Poly(I:C) adjuvanted subunit influenza vaccine induced similar antigen-specific immune responses compared to vaccine alone when delivered to the skin by microneedles. However, imiquimod-adjuvanted vaccine elicited higher levels of serum IgG2a antibodies and increased hemagglutination inhibition titers compared to vaccine alone, suggesting enhanced induction of functional antibodies. In addition, imiquimod-adjuvanted vaccine induced a robust IFN-γ cellular response. These responses correlated with improved protection compared to influenza subunit vaccine alone, as well as reduced viral replication and production of pro-inflammatory cytokines in the lungs. The finding that microneedle delivery of imiquimod with influenza subunit vaccine induces improved immune responses compared to vaccine alone supports the use of TLR7 ligands as adjuvants for skin-based influenza vaccines.
Indirect rapid prototyping of antibacterial acid anhydride copolymer microneedles.
Boehm Ryan D,Miller Philip R,Singh Ritika,Shah Akash,Stafslien Shane,Daniels Justin,Narayan Roger J
Microneedles are needle-like projections with microscale features that may be used for transdermal delivery of a variety of pharmacologic agents, including antibacterial agents. In the study described in this paper, an indirect rapid prototyping approach involving a combination of visible light dynamic mask micro-stereolithography and micromolding was used to prepare microneedle arrays out of a biodegradable acid anhydride copolymer, Gantrez(®) AN 169 BF. Fourier transform infrared spectroscopy, energy dispersive x-ray spectrometry and nanoindentation studies were performed to evaluate the chemical and mechanical properties of the Gantrez(®) AN 169 BF material. Agar plating studies were used to evaluate the in vitro antimicrobial performance of these arrays against Bacillus subtilis, Candida albicans, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. Large zones of growth inhibition were noted for Escherichia coli, S. aureus, Enterococcus faecalis and B. subtilis. The performance of Gantrez(®) AN 169 BF against several bacteria suggests that biodegradable acid anhydride copolymer microneedle arrays prepared using visible light dynamic mask micro-stereolithography micromolding may be useful for treating a variety of skin infections.
Stability of influenza vaccine coated onto microneedles.
Choi Hyo-Jick,Yoo Dae-Goon,Bondy Brian J,Quan Fu-Shi,Compans Richard W,Kang Sang-Moo,Prausnitz Mark R
A microneedle patch coated with vaccine simplifies vaccination by using a patch-based delivery method and targets vaccination to the skin for superior immunogenicity compared to intramuscular injection. Previous studies of microneedles have demonstrated effective vaccination using freshly prepared microneedles, but the issue of long-term vaccine stability has received only limited attention. Here, we studied the long-term stability of microneedles coated with whole inactivated influenza vaccine guided by the hypothesis that crystallization and phase separation of the microneedle coating matrix damages influenza vaccine coated onto microneedles. In vitro studies showed that the vaccine lost stability as measured by hemagglutination activity in proportion to the degree of coating matrix crystallization and phase separation. Transmission electron microscopy similarly showed damaged morphology of the inactivated virus vaccine associated with crystallization. In vivo assessment of immune response and protective efficacy in mice further showed reduced vaccine immunogenicity after influenza vaccination using microneedles with crystallized or phase-separated coatings. This work shows that crystallization and phase separation of the dried coating matrix are important factors affecting long-term stability of influenza vaccine-coated microneedles.
Treatment of striae distensae using needling therapy: a pilot study.
Park Kui Young,Kim Hyun Kyu,Kim Sung Eun,Kim Beom Joon,Kim Myeung Nam
Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.]
BACKGROUND:Striae distensae are dermal scars characterized by flattening and atrophy of the epidermis. Although many treatment modalities have been attempted with variable results, there is no criterion standard treatment modality for striae distensae. OBJECTIVES:To evaluate the effectiveness and safety of a disk microneedle therapy system (DTS) in the treatment of striae distensae. MATERIALS AND METHODS:Sixteen Korean volunteers with striae distensae alba or rubra were enrolled. Patients received three treatments using a DTS at 4-week intervals. Clinical response to treatment was assessed by comparing pre- and post-treatment clinical photographs, skin biopsies, and patient satisfaction scores. Clinical improvement was assessed using the quartile grading scale. RESULTS:Marked to excellent improvement was noted in seven (43.8%) patients, with minimal to moderate improvement in the remaining nine. Patient satisfaction scores showed that six (37.5%) patients were highly satisfied, eight (50.0%) were somewhat satisfied, and two (12.5%) were unsatisfied. There were no significant side effects except mild pain, erythema, and spotty bleeding. CONCLUSION:Disk microneedle therapy system (DTS) can be effectively and safely used in the treatment of striae distensae.
Delivery systems for intradermal vaccination.
Kim Y C,Jarrahian C,Zehrung D,Mitragotri S,Prausnitz M R
Current topics in microbiology and immunology
Intradermal (ID) vaccination can offer improved immunity and simpler logistics of delivery, but its use in medicine is limited by the need for simple, reliable methods of ID delivery. ID injection by the Mantoux technique requires special training and may not reliably target skin, but is nonetheless used currently for BCG and rabies vaccination. Scarification using a bifurcated needle was extensively used for smallpox eradication, but provides variable and inefficient delivery into the skin. Recently, ID vaccination has been simplified by introduction of a simple-to-use hollow microneedle that has been approved for ID injection of influenza vaccine in Europe. Various designs of hollow microneedles have been studied preclinically and in humans. Vaccines can also be injected into skin using needle-free devices, such as jet injection, which is receiving renewed clinical attention for ID vaccination. Projectile delivery using powder and gold particles (i.e., gene gun) have also been used clinically for ID vaccination. Building off the scarification approach, a number of preclinical studies have examined solid microneedle patches for use with vaccine coated onto metal microneedles, encapsulated within dissolving microneedles or added topically to skin after microneedle pretreatment, as well as adapting tattoo guns for ID vaccination. Finally, technologies designed to increase skin permeability in combination with a vaccine patch have been studied through the use of skin abrasion, ultrasound, electroporation, chemical enhancers, and thermal ablation. The prospects for bringing ID vaccination into more widespread clinical practice are encouraging, given the large number of technologies for ID delivery under development.
Hydrogel swelling as a trigger to release biodegradable polymer microneedles in skin.
Kim MinYoung,Jung Bokyung,Park Jung-Hwan
Biodegradable polymeric microneedles were developed as a method for achieving sustained transdermal drug release. These microneedles have potential as a patient-friendly substitute for conventional sustained release methods. However, they have limitations related to the difficulty of achieving separation of the needles into the skin. We demonstrated that microneedle separation into the skin was mediated by hydrogel swelling in response to contact with body fluid after the needles were inserted into the skin. The hydrogel microparticles were synthesized by an emulsification method using poly-N-isopropylacrylamide (PNIPAAm). The microneedles were fabricated by micromolding poly-lactic-co-glycolic acid (PLGA) after filling the cavities of the mold with the hydrogel microparticles. The failure of microneedle tips caused by hydrogel swelling was studied in regard to contact with water, insertion of microneedles into porcine cadaver skin in vitro, stress-strain behavior, and insertion into the back skin of a hairless mouse in vivo. The drug delivery property of the hydrogel particles was investigated qualitatively by inserting polymer microneedles into porcine cadaver skin in vitro, and the sustained release property of PLGA microneedles containing hydrogel microparticles was studied quantitatively using the Franz cell model. The hydrogel particles absorbed water quickly, resulting in the cracking of the microneedles due to the difference in volume expansion between the needle matrix polymer and the hydrogel particles. The swollen particles caused the microneedles to totally breakdown, leaving the microneedle tips in the porcine cadaver skin in vitro and in the hairless mouse skin in vivo. Model drugs encapsulated in biodegradable polymer microneedles and hydrogel microparticles were successfully delivered by releasing microneedles into the skin.
Microneedles for drug and vaccine delivery.
Kim Yeu-Chun,Park Jung-Hwan,Prausnitz Mark R
Advanced drug delivery reviews
Microneedles were first conceptualized for drug delivery many decades ago, but only became the subject of significant research starting in the mid-1990's when microfabrication technology enabled their manufacture as (i) solid microneedles for skin pretreatment to increase skin permeability, (ii) microneedles coated with drug that dissolves off in the skin, (iii) polymer microneedles that encapsulate drug and fully dissolve in the skin and (iv) hollow microneedles for drug infusion into the skin. As shown in more than 350 papers now published in the field, microneedles have been used to deliver a broad range of different low molecular weight drugs, biotherapeutics and vaccines, including published human studies with a number of small-molecule and protein drugs and vaccines. Influenza vaccination using a hollow microneedle is in widespread clinical use and a number of solid microneedle products are sold for cosmetic purposes. In addition to applications in the skin, microneedles have also been adapted for delivery of bioactives into the eye and into cells. Successful application of microneedles depends on device function that facilitates microneedle insertion and possible infusion into skin, skin recovery after microneedle removal, and drug stability during manufacturing, storage and delivery, and on patient outcomes, including lack of pain, skin irritation and skin infection, in addition to drug efficacy and safety. Building off a strong technology base and multiple demonstrations of successful drug delivery, microneedles are poised to advance further into clinical practice to enable better pharmaceutical therapies, vaccination and other applications.
Drawing lithography for microneedles: a review of fundamentals and biomedical applications.
Lee Kwang,Jung Hyungil
A microneedle is a three-dimensional (3D) micromechanical structure and has been in the spotlight recently as a drug delivery system (DDS). Because a microneedle delivers the target drug after penetrating the skin barrier, the therapeutic effects of microneedles proceed from its 3D structural geometry. Various types of microneedles have been fabricated using subtractive micromanufacturing methods which are based on the inherently planar two-dimensional (2D) geometries. However, traditional subtractive processes are limited for flexible structural microneedles and makes functional biomedical applications for efficient drug delivery difficult. The authors of the present study propose drawing lithography as a unique additive process for the fabrication of a microneedle directly from 2D planar substrates, thus overcoming a subtractive process shortcoming. The present article provides the first overview of the principal drawing lithography technology: fundamentals and biomedical applications. The continuous drawing technique for an ultrahigh-aspect ratio (UHAR) hollow microneedle, stepwise controlled drawing technique for a dissolving microneedle, and drawing technique with antidromic isolation for a hybrid electro-microneedle (HEM) are reviewed, and efficient biomedical applications by drawing lithography-mediated microneedles as an innovative drug and gene delivery system are described. Drawing lithography herein can provide a great breakthrough in the development of materials science and biotechnology.
Systematic assessment of microneedle injection into the mouse cornea.
Matthaei Mario,Meng Huan,Bhutto Imran,Xu Qingguo,Boelke Edwin,Hanes Justin,Jun Albert S
European journal of medical research
BACKGROUND:Corneal intrastromal injection is an important mode of gene-vector application to subepithelial layers. In a mouse model, this procedure is substantially complicated by the reduced corneal dimensions. Furthermore, it may be difficult to estimate the corneal area reached by the volume of a single injection. This study aimed to investigate intrastromal injections into the mouse cornea using different microneedles and to quantify the effect of injecting varying volumes. A reproducible injection technique is described. METHODS:Forty eyes of 20 129 Sv/J mice were tested. India ink was intrastromally injected using 30° beveled 33 G needles, tri-surface 25° beveled 35 G needles, or hand-pulled and 25° beveled glass needles. Each eye received a single injection of a volume of 1 or 2 μL. Corneoscleral buttons were fixed and flat mounted for computer-assisted quantification of the affected corneal area. Histological assessment was performed to investigate the intrastromal location of the injected dye. RESULTS:A mean corneal area of 5.0 ± 1.4 mm(2) (mean ± SD) and 7.7 ± 1.4 mm(2) was covered by intrastromal injections of 1 and 2 μL, respectively. The mean percentage of total corneal area reached ranged from 39% to 53% for 1 μL injections, and from 65% to 81% for 2 μL injections. Injections using the 33 G needles tended to provide the highest distribution area. Perforation rates were 8% for 30° beveled 33 G needles and 44% for tri-surface beveled 35 G needles. No perforation was observed with glass needle; however, intrastromal breakage of needle tips was noted in 25% of these cases. CONCLUSIONS:Intracorneal injection using a 30° beveled 33 G needle was safe and effective. The use of tri-surface beveled 35 G needles substantially increased the number of corneal perforations. Glass needles may break inside the corneal stroma. Injections of 1 μL and 2 μL resulted in an overall mean of 49% and 73% respectively of total corneal area involved.
Microneedle-based analysis of the micromechanics of the metaphase spindle assembled in Xenopus laevis egg extracts.
Shimamoto Yuta,Kapoor Tarun M
To explain how micrometer-sized cellular structures generate and respond to forces, we need to characterize their micromechanical properties. Here we provide a protocol to build and use a dual force-calibrated microneedle-based setup to quantitatively analyze the micromechanics of a metaphase spindle assembled in Xenopus laevis egg extracts. This cell-free extract system allows for controlled biochemical perturbations of spindle components. We describe how the microneedles are prepared and how they can be used to apply and measure forces. A multimode imaging system allows the tracking of microtubules, chromosomes and needle tips. This setup can be used to analyze the viscoelastic properties of the spindle on timescales ranging from minutes to sub-seconds. A typical experiment, along with data analysis, is also detailed. We anticipate that our protocol can be readily extended to analyze the micromechanics of other cellular structures assembled in cell-free extracts. The entire procedure can take 3-4 d.
Pharmacokinetics and postprandial glycemic excursions following insulin lispro delivered by intradermal microneedle or subcutaneous infusion.
McVey Elaine,Hirsch Laurence,Sutter Diane E,Kapitza Christoph,Dellweg Sibylle,Clair Janina,Rebrin Kerstin,Judge Kevin,Pettis Ronald J
Journal of diabetes science and technology
BACKGROUND:Intradermal (ID) delivery has been shown to accelerate insulin pharmacokinetics (PK). We compared the PK and pharmacodynamic (PD) effects of insulin lispro administered before two daily standardized solid mixed meals (breakfast and lunch), using microneedle-based ID or traditional subcutaneous (SC) delivery. METHOD:The study included 22 subjects with type 1 diabetes in an eight-arm full crossover block design. One arm established each subject's optimal meal dose. In six additional arms, the optimal, higher, and lower doses (+30%, -30%) were each given ID and SC delivery, in random order. The final arm assessed earlier timing for the ID optimal dose (-12 versus -2 min). The PK/PD data were collected for 6 h following meals. Intravenous basal regular insulin was given throughout, and premeal blood glucose (BG) adjusted to 115 mg/dl. RESULTS:The primary end point, postprandial time in range (70-180 mg/dl), showed no route-based differences with a high level of overall BG control for both SC and ID delivery. Secondary insulin PK end points showed more rapid ID availability versus SC across doses and meals (∆Tmax -16 min, ∆T50rising -7 min, ∆T50falling -30 min, all p < .05). Both intrasubject and intersubject variability for ID Tmax were significantly lower. Intradermal delivery showed modest, statistically significant secondary PD differences across doses and meals, generally within 90-120 min postprandially (∆12 mg/dl BG at 90 min, ∆7 mg/dl BGmax, ∆7 mg/dl mean BG 0-2 h, all p < .05). CONCLUSIONS:This study indicates that ID insulin delivery is superior to SC delivery in speed of systemic availability and PK consistency and may improve postprandial glucose control.
Development of lidocaine-coated microneedle product for rapid, safe, and prolonged local analgesic action.
Zhang Ying,Brown Ken,Siebenaler Kris,Determan Amy,Dohmeier Daniel,Hansen Kris
PURPOSE:To demonstrate rapid (~1 min) lidocaine delivery using 3M's solid microstructured transdermal system (sMTS) for prolonged, local analgesic action. METHODS:Polymeric microneedles were fabricated via injection molding and then dip-coated using an aqueous lidocaine formulation. The amount of lidocaine coated onto the microneedles was determined by high performance liquid chromatography (HPLC). To assess drug delivery and dermal pharmacokinetics, lidocaine-coated microneedles were inserted into domestic swine. Skin punch biopsies were collected and analyzed to determine lidocaine concentration in skin using HPLC-mass spectrometry (LC-MS). Commercial lidocaine/prilocaine EMLA (Eutectic Mixture of Local Anesthetic) cream was used as comparative control. RESULTS:Lidocaine dissolves rapidly off the microneedles and into skin such that the 1-min wear time achieves or exceeds lidocaine tissue levels needed to cause analgesia. This therapeutic threshold (100 ng/mg) was estimated by measuring the total amount of lidocaine and prilocaine in skin following a 1 h EMLA application. When co-formulated with 0.03 wt% vasoconstrictor-epinephrine, the concentration of lidocaine in tissue was maintained above 100 ng/mg for approximately 90 min. CONCLUSIONS:3M's sMTS can be used to provide rapid delivery of lidocaine for local analgesia up to 90 min.
Delivery of salmon calcitonin using a microneedle patch.
Tas Cetin,Mansoor Saffar,Kalluri Haripriya,Zarnitsyn Vladimir G,Choi Seong-O,Banga Ajay K,Prausnitz Mark R
International journal of pharmaceutics
Peptides and polypeptides have important pharmacological properties but only a limited number have been exploited as therapeutics because of problems related to their delivery. Most of these drugs require a parenteral delivery system which introduces the problems of pain, possible infection, and expertise required to carry out an injection. The aim of this study was to develop a transdermal patch containing microneedles (MNs) coated with a peptide drug, salmon calcitonin (sCT), as an alternative to traditional subcutaneous and nasal delivery routes. Quantitative analysis of sCT after coating and drying onto microneedles was performed with a validated HPLC method. In vivo studies were carried out on hairless rats and serum levels of sCT were determined by ELISA. The AUC value of MNs coated with a trehalose-containing formulation (250 ± 83 ng/mL min) was not significantly different as compared to subcutaneous injections (403 ± 253 ng/mL min), but approximately 13 times higher than nasal administration (18.4 ± 14.5 ng/mL min). T(max) (7.5 ± 5 min) values for MN mediated administration were 50% shorter than subcutaneous injections (15 min), possibly due to rapid sCT dissolution and absorption by dermal capillaries. These results suggest that with further optimization of coating formulations, microneedles may enable administration of sCT and other peptides without the need for hypodermic injections.
Dissolving polymeric microneedle arrays for electrically assisted transdermal drug delivery.
Garland Martin J,Caffarel-Salvador Ester,Migalska Katarzyna,Woolfson A David,Donnelly Ryan F
Journal of controlled release : official journal of the Controlled Release Society
It has recently been proposed that the combination of skin barrier impairment using microneedles (MNs) coupled with iontophoresis (ITP) may broaden the range of drugs suitable for transdermal delivery, as well as enabling the rate of delivery to be achieved with precise electronic control. However, no reports exist on the combination of ITP with in situ drug loaded polymeric MN delivery systems. Furthermore, although a number of studies have highlighted the importance of MN design for transdermal drug delivery enhancement, to date, there has been no systematic investigation of the influence of MN geometry on the performance of polymeric MN arrays which are designed to remain in contact with the skin during the period of drug delivery. As such, for the first time, this study reports on the effect of MN heigth and MN density upon the transdermal delivery of small hydrophilic compounds (theophylline, methylene blue, and fluorescein sodium) across neonatal porcine skin in vitro, with the optimised MN array design evaluated for its potential in the electrically faciliatated delivery of peptide (bovine insulin) and protein (fluorescein isothiocyanate-labelled bovine serum albumin (FTIC-BSA)) macromolecules. The results of the in vitro drug release investigations revealed that the extent of transdermal delivery was dependent upon the design of the MN array employed, whereby an increase in MN height and an increase in MN density led to an increase in the extent of transdermal drug delivery achieved 6h after MN application. Overall, the in vitro permeation studies revealed that the MN design containing 361 MNs/cm(2) of 600 μm height resulted in the greatest extent of transdermal drug delivery. As such, this design was evaluated for its potential in the MN mediated iontophoretic transdermal delivery. Whilst the combination of MN and ITP did not further enhance the extent of small molecular weight solute delivery, the extent of peptide/protein release was significantly enhanced when ITP was used in combination of the soluble PMVE/MA MN arrays. For example, the cumulative amount of insulin permeated across neonatal porcine skin at 6h was found to be approximately 150 μg (3.25%), 227 μg (4.85%) and 462 μg (9.87%) for ITP, MN, and MN/ITP delivery strategies, respectively. Similarly, the cumulative amount of FTIC-BSA delivered across neonatal porcine skin after a 6h period was found to be approximately 110 μg (4.53%) for MN alone and 326 μg (13.40%) for MN in combination with anodal ITP (p<0.001). As such, drug loaded soluble PMVE/MA MN arrays show promise for the electrically controlled transdermal delivery of biomacromolecules in a simple, one-step approach.
A combined approach of vesicle formulations and microneedle arrays for transcutaneous immunization against hepatitis B virus.
Hirschberg Hoang,van Kuijk Sandra,Loch Jessica,Jiskoot Wim,Bouwstra Joke,Kersten Gideon,Amorij Jean-Pierre
European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences
In the search for an optimal approach for the transcutaneous immunization (TCI) of hepatitis B surface antigen (HBsAg), two vesicle formulations, L595 vesicles (composed of sucrose-laurate ester and octaoxyethylene-laurate ester) and sPC vesicles (composed of soybean-phosphatidylcholine and Span-80) were prepared and characterized in vitro and in vivo. HBsAg was associated to the vesicles, resulting in sPC-HBsAg vesicles (±170nm) with 79% HBsAg association and L595-HBsAg vesicles (±75nm) with only 29% HBsAg association. The vesicles induced in mice via TCI an antibody response only when the skin was pretreated with microneedles. This response was improved by the adjuvant cholera toxin. The sPC-HBsAg vesicle formulations showed to be the most immunogenic for TCI, which was related to the higher degree of HBsAg association.
Multidrug release based on microneedle arrays filled with pH-responsive PLGA hollow microspheres.
Ke Cherng-Jyh,Lin Yi-Jou,Hu Yi-Chen,Chiang Wei-Lun,Chen Ko-Jie,Yang Wen-Cheng,Liu Hao-Li,Fu Chien-Chung,Sung Hsing-Wen
This work presents an approach to codelivering transdermally two model drugs, Alexa 488 and Cy5, in sequence, based on a system of polyvinylpyrrolidone microneedles (PVP MNs) that contain pH-responsive poly(d,l-lactic-co-glycolic acid) hollow microspheres (PLGA HMs). The MN system provides the green fluorescence of Alexa 488 in PVP MNs, the red fluorescence of the DiI-labeled PLGA shell of HMs, and the cyan fluorescence of Cy5 in their aqueous core. Combined together, the prepared MN arrays support the localization of the HMs and the monitoring of the release profiles of model drugs within the skin tissues. The key component of this system is NaHCO(3), which can be easily incorporated into HMs. After HMs are treated with an acidic solution (simulating the skin pH environment), protons (H(+)) can rapidly diffuse through the free volume in the PLGA shells to react with NaHCO(3) and form a large number of CO(2) bubbles. This effect generates pressure inside the HMs and creates pores inside their PLGA shells, releasing the encapsulated Cy5. Test MNs were strong enough to be inserted into rat skin without breaking. The PVP MNs were significantly dissolved within minutes, and the first model drug Alexa 488, together with HMs, were successfully deposited into the tissues. Once in the acidic environment of the skin, the released HMs started to release Cy5 and continued to spread throughout the neighboring tissues, in a second step of the release of the drug. This approach can be used clinically to codeliver sequentially and transcutaneously a broad range of drugs.
The development and characteristics of novel microneedle arrays fabricated from hyaluronic acid, and their application in the transdermal delivery of insulin.
Liu Shu,Jin Mei-na,Quan Ying-shu,Kamiyama Fumio,Katsumi Hidemasa,Sakane Toshiyasu,Yamamoto Akira
Journal of controlled release : official journal of the Controlled Release Society
The aim of the present study was to develop novel insulin-loaded microneedle arrays (MNs) fabricated from hyaluronic acid (HA), and characterize their applicability in the transdermal delivery of insulin. The shape of MNs was observed via scanning electron microscopy. The characteristics of these novel insulin-loaded MNs, including hygroscopy, stability, drug release profiles, and dissolution properties, were evaluated from a clinical application point-of-view. Transepidermal water loss (TEWL) was measured to investigate the piercing properties of MNs, and the recovery of the skin barrier after the removal of MNs to confirm their safety. Additionally, the transdermal absorption of insulin from MNs was examined via an in vivo absorption study in diabetic rats. The length of MNs was 800 μm with a base diameter of 160 μm and a tip diameter of 40 μm. MNs were found to maintain their skin piercing abilities for at least 1h, even at a relative humidity of 75%. After storing insulin-loaded MNs for a month at -40, 4, 20, and 40 °C, more than 90% of insulin remained in MNs at all temperatures, indicating that insulin is highly stable in MNs at these storage conditions. It was also found that insulin is rapidly released from MNs via an in vitro release study. These findings were consistent with the complete dissolution of MNs within 1h of application to rat skin in vivo. Therefore, the novel HA MNs possess self-dissolving properties after their dermal application, and insulin appears to be rapidly released from these MNs. A significant increase in TEWL was observed after the application of MNs. However, this parameter recovered back to baseline within 24h after the removal of MNs. These findings indicate that the transdermal transport pathway of insulin, which was created by the MNs, disappeared within 24h, and that the skin damage induced by the MNs was reversible. Furthermore, a dose-dependent hypoglycemic effect and transdermal delivery of insulin were observed after a dermal treatment with insulin-loaded MNs in vivo. A continuous hypoglycemic effect was observed after 0.25 IU of insulin was administered to skin via MNs. Additionally, lower peak plasma insulin levels, but higher plasma insulin concentrations after 2 h, were achieved with 0.25 IU of insulin administered via MNs as compared to the subcutaneous administration of insulin of the same dose. Pharmacodynamic and pharmacokinetic parameters indicated that insulin administered via MNs was almost completely absorbed from the skin into the systemic circulation, and that the hypoglycemic effect of insulin-loaded MNs was almost similar to that of the subcutaneous injection of insulin. These findings indicate that the novel insulin-loaded MNs fabricated from HA are a very useful alternative method of delivering insulin via the skin into the systemic circulation without inducing serious skin damage. Therefore, HA MNs may be an effective and safe method of transdermal insulin delivery in the clinic.
Microneedle-mediated transdermal bacteriophage delivery.
Ryan Elizabeth,Garland Martin J,Singh Thakur Raghu Raj,Bambury Eoin,O'Dea John,Migalska Katarzyna,Gorman Sean P,McCarthy Helen O,Gilmore Brendan F,Donnelly Ryan F
European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences
Interest in bacteriophages as therapeutic agents has recently been reawakened. Parenteral delivery is the most routinely-employed method of administration. However, injection of phages has numerous disadvantages, such as the requirement of a health professional for administration and the possibility of cross-contamination. Transdermal delivery offers one potential means of overcoming many of these problems. The present study utilized a novel poly (carbonate) (PC) hollow microneedle (MN) device for the transdermal delivery of Escherichia coli-specific T4 bacteriophages both in vitro and in vivo. MN successfully achieved bacteriophage delivery in vitro across dermatomed and full thickness skin. A concentration of 2.67 × 10(6)PFU/ml (plaque forming units per ml) was detected in the receiver compartment when delivered across dermatomed skin and 4.0 × 10(3)PFU/ml was detected in the receiver compartment when delivered across full thickness skin. An in vivo study resulted in 4.13 × 10(3)PFU/ml being detected in blood 30 min following initial MN-mediated phage administration. Clearance occurred rapidly, with phages being completely cleared from the systemic circulation within 24h, which was expected in the absence of infection. We have shown here that MN-mediated delivery allows successful systemic phage absorption. Accordingly, bacteriophage-based therapeutics may now have an alternative route for systemic delivery. Once fully-investigated, this could lead to more widespread investigation of these interesting therapeutic viruses.
Influence of skin model on in vitro performance of drug-loaded soluble microneedle arrays.
Garland Martin J,Migalska Katarzyna,Tuan-Mahmood Tuan-Mazlelaa,Raghu Raj Singh Thakur,Majithija Rita,Caffarel-Salvador Ester,McCrudden Cian M,McCarthy Helen O,David Woolfson A,Donnelly Ryan F
International journal of pharmaceutics
A plethora of studies have described the in vitro assessment of dissolving microneedle (MN) arrays for enhanced transdermal drug delivery, utilising a wide variety of model membranes as a representation of the skin barrier. However, to date, no discussion has taken place with regard to the choice of model skin membrane and the impact this may have on the evaluation of MN performance. In this study, we have, for the first time, critically assessed the most common types of in vitro skin permeation models - a synthetic hydrophobic membrane (Silescol(®) of 75 μm) and neonatal porcine skin of definable thickness (300-350 μm and 700-750 μm) - for evaluating the performance of drug loaded dissolving poly (methyl vinyl ether co maleic acid) (PMVE/MA) MN arrays. It was found that the choice of in vitro skin model had a significant effect on the permeation of a wide range of small hydrophilic molecules released from dissolving MNs. For example, when Silescol(®) was used as the model membrane, the cumulative percentage permeation of methylene blue 24h after the application of dissolvable MNs was found to be only approximately 3.7% of the total methylene blue loaded into the MN device. In comparison, when dermatomed and full thickness neonatal porcine skin were used as a skin model, approximately 67.4% and 47.5% of methylene blue loaded into the MN device was delivered across the skin 24h after the application of MN arrays, respectively. The application of methylene blue loaded MN arrays in a rat model in vivo revealed that the extent of MN-mediated percutaneous delivery achieved was most similar to that predicted from the in vitro investigations employing dermatomed neonatal porcine skin (300-350 μm) as the model skin membrane. On the basis of these results, a wider discussion within the MN community will be necessary to standardise the experimental protocols used for the evaluation and comparison of MN devices.
Flux of ionic dyes across microneedle-treated skin: effect of molecular characteristics.
Gomaa Yasmine A,Garland Martin J,McInnes Fiona J,Donnelly Ryan F,El-Khordagui Labiba K,Wilson Clive G
International journal of pharmaceutics
Drug flux across microneedle (MN)-treated skin is influenced by the characteristics of the MN array, formed microconduits and physicochemical properties of the drug molecules in addition to the overall diffusional resistance of microconduits and viable tissue. Relative implication of these factors has not been fully explored. In the present study, the in vitro permeation of a series of six structurally related ionic xanthene dyes with different molecular weights (MW) and chemical substituents, across polymer MN-pretreated porcine skin was investigated in relation of their molecular characteristics. Dyes equilibrium solubility, partition coefficient in both n-octanol or porcine skin/aqueous system, and dissociation constants were determined. Results indicated that for rhodamine dyes, skin permeation of the zwitterionic form which predominates at physiological pH, was significantly reduced by an increase in MW, the skin thickness and by the presence of the chemically reactive isothiocyanate substituent. These factors were generally shown to override the aqueous solubility, an important determinant of drug diffusion in an aqueous milieu. The data obtained provided more insight into the mechanism of drug permeation across MN-treated skin, which is of importance to both the design of MN-based transdermal drug delivery systems and of relevance to skin permeation research.
Targeted administration into the suprachoroidal space using a microneedle for drug delivery to the posterior segment of the eye.
Patel Samirkumar R,Berezovsky Damian E,McCarey Bernard E,Zarnitsyn Vladimir,Edelhauser Henry F,Prausnitz Mark R
Investigative ophthalmology & visual science
PURPOSE:This study seeks to determine the intraocular pharmacokinetics of molecules and particles injected into the suprachoroidal space of the rabbit eye in vivo using a hollow microneedle. METHODS:Suprachoroidal injections of fluorescein and fluorescently tagged dextrans (40 and 250 kDa), bevacizumab, and polymeric particles (20 nm to 10 μm in diameter) were performed using microneedles in New Zealand white rabbits. The fluorescence intensity within the eye was monitored in each animal using an ocular fluorophotometer to determine the distribution of the injected material in the eye over time as compared with intravitreal injection of fluorescein. Fundus photography and histology were performed as well. RESULTS:Molecules and particles injected near the limbus using a microneedle flowed circumferentially around the eye within the suprachoroidal space. By targeting the suprachoroidal space, the concentration of injected materials was at least 10-fold higher in the back of the eye tissues than in anterior tissues. In contrast, intravitreal injection of fluorescein targeted the vitreous humor with no significant selectivity for posterior versus anterior segment tissues. Half-lives in the suprachoroidal space for molecules of molecular weight from 0.3 to 250 kDa ranged from 1.2 to 7.9 hours. In contrast, particles ranging in size from 20 nm to 10 μm remained primarily in the suprachoroidal space and choroid for a period of months and did not clear the eye. No adverse effects of injection into the suprachoroidal space were observed. CONCLUSION:Injection into the suprachoroidal space using a microneedle offers a simple and minimally invasive way to target the delivery of drugs to the choroid and retina.
Microneedle and mucosal delivery of influenza vaccines.
Kang Sang-Moo,Song Jae-Min,Kim Yeu-Chun
Expert review of vaccines
In recent years with the threat of pandemic influenza and other public health needs, alternative vaccination methods other than intramuscular immunization have received great attention. The skin and mucosal surfaces are attractive sites probably because of both noninvasive access to the vaccine delivery and unique immunological responses. Intradermal vaccines using a microinjection system (BD Soluvia(TM)) and intranasal vaccines (FluMist®) are licensed. As a new vaccination method, solid microneedles have been developed using a simple device that may be suitable for self-administration. Because coated microneedle influenza vaccines are administered in the solid state, developing formulations maintaining the stability of influenza vaccines is an important issue to be considered. Marketable microneedle devices and clinical trials remain to be developed. Other alternative mucosal routes such as oral and intranasal delivery systems are also attractive for inducing cross-protective mucosal immunity, but effective non-live mucosal vaccines remain to be developed.
Challenges and strategies in developing microneedle patches for transdermal delivery of protein and peptide therapeutics.
Wu Fei,Yang Sixing,Yuan Weien,Jin Tuo
Current pharmaceutical biotechnology
The birth of microneedles, an array of needles sufficiently long to penetrate epidermis but small enough to do not cause skin injury and pain feeling, has offered a highly promising solution for non-invasive delivery of protein and peptide drugs, a long-cherished desire over eighty years. However, the attempts to develop clinically feasible microneedle transdermal delivery methods encountered series of difficulties, for which a decade research efforts have yet to result in a single product. Microneedles may be incorporated into devices as skin pre-treatment tools, skin microinjectors as well as transdermal patches by their functions in drug delivery. They may also be categorized to insoluble solid microneedles, hollow microneedles, soluble/degradable solid microneedles and phase-transition microneedles by their structure and forming materials. This review article is aimed to update the progress and discuss the technical challenges raised in developing protein/peptide loaded microneedle patches.
Safety of a novel microneedle device applied to facial skin: a subject- and rater-blinded, sham-controlled, randomized trial.
Hoesly Fridolin J,Borovicka Judy,Gordon Jennifer,Nardone Beatrice,Holbrook Jaimee S,Pace Natalie,Ibrahim Omer,Bolotin Diana,Warycha Melanie,Kwasny Mary,West Dennis,Alam Murad
Archives of dermatology
OBJECTIVE:To assess the safety of a novel microneedle device on facial skin of healthy individuals of all Fitzpatrick skin types. DESIGN:Subject- and live rater–blinded, sham-controlled, randomized trial. SETTING:University-based ambulatory dermatology service providing both primary and referral care. PARTICIPANTS:Healthy adults recruited from postings. INTERVENTION:Device or sham applied with finger pressure to the right or left sides, respectively, of the participants' lateral forehead, temple, and nasolabial fold. At the 24-hour visit, a larger area (3 × 3 matrix) at the central forehead was treated with the device, and the participants applied the device to their chins. MAIN OUTCOME MEASURE:Live blinded rater determination of local skin reaction scores (SRSs). RESULTS:At the 5-minute skin assessment, the median SRS was 1 for all skin type and age groups. There was no median pain score higher than 1 for any age or skin type group. For the sham device, median SRSs were 0 at all time points for all age and skin type groups. Mean SRSs for the device and sham were significantly different only for the lateral forehead at 5 and 30 minutes (P = .04). CONCLUSIONS:The microneedle device appears to be safe and well tolerated in both sexes and various skin types and ages. Facial skin application of the device elicits mild, self-limited, and rapidly resolving erythema marginally greater than that associated with the sham control.
Evaluation of the clinical efficacy of fractional radiofrequency microneedle treatment in acne scars and large facial pores.
Cho Soo Ick,Chung Bo Young,Choi Min Gyu,Baek Ji Hwoon,Cho Hee Jin,Park Chun Wook,Lee Cheol Heon,Kim Hye One
Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.]
BACKGROUND:Fractional technology overcomes the problems of ablative lasers, such as inaccurate depth control and damage to the epidermis. Minimally invasive fractional radiofrequency microneedle devices allow for more-selective heating of the dermis. OBJECTIVE:To evaluate the clinical efficacy of fractional radiofrequency microneedle (ERM) treatment in acne scars and large facial pores. MATERIALS AND METHODS:Thirty patients with acne scars and large facial pores were enrolled. Bipolar radiofrequency energy was delivered to the skin through the electrodes of the FRM device. Skin lesions were evaluated according to grade of acne scars, Investigator Global Assessment of large pores, skin surface roughness, transepidermal water loss (TEWL), dermal density, microscopic and composite image, sebum measurement, and questionnaires regarding patient satisfaction. RESULTS:The grade of acne scars and Investigator Global Assessment of large pores improved in more than 70% of all patients. Skin surface roughness, dermal density, and microscopic and composite images also improved, whereas TEWL and sebum measurement did not change. CONCLUSION:Clinical improvement from FRM treatment appeared to be related to dermal matrix regeneration. FRM treatment may be effective in improving acne scars and facial pores.
Inhibition of CD44 gene expression in human skin models, using self-delivery short interfering RNA administered by dissolvable microneedle arrays.
Lara Maria Fernanda,González-González Emilio,Speaker Tycho J,Hickerson Robyn P,Leake Devin,Milstone Leonard M,Contag Christopher H,Kaspar Roger L
Human gene therapy
Treatment of skin disorders with short interfering RNA (siRNA)-based therapeutics requires the development of effective delivery methodologies that reach target cells in affected tissues. Successful delivery of functional siRNA to the epidermis requires (1) crossing the stratum corneum, (2) transfer across the keratinocyte membrane, followed by (3) incorporation into the RNA-induced silencing complex. We have previously demonstrated that treatment with microneedle arrays loaded with self-delivery siRNA (sd-siRNA) can achieve inhibition of reporter gene expression in a transgenic mouse model. Furthermore, treatment of human cultured epidermal equivalents with sd-siRNA resulted in inhibition of target gene expression. Here, we demonstrate inhibition of CD44, a gene that is uniformly expressed throughout the epidermis, by sd-siRNA both in vitro (cultured human epidermal skin equivalents) and in vivo (full-thickness human skin equivalents xenografted on immunocompromised mice). Treatment of human skin equivalents with CD44 sd-siRNA markedly decreased CD44 mRNA levels, which led to a reduction of the target protein as confirmed by immunodetection in epidermal equivalent sections with a CD44-specific antibody. Taken together, these results demonstrate that sd-siRNA, delivered by microneedle arrays, can reduce expression of a targeted endogenous gene in a human skin xenograft model.
Hydrogel-Forming Microneedle Arrays for Enhanced Transdermal Drug Delivery.
Donnelly Ryan F,Singh Thakur Raghu Raj,Garland Martin J,Migalska Katarzyna,Majithiya Rita,McCrudden Cian M,Kole Prashant Laxman,Mahmood Tuan Mazlelaa Tuan,McCarthy Helen O,Woolfson A David
Advanced functional materials
Unique microneedle arrays prepared from crosslinked polymers, which contain no drug themselves, are described. They rapidly take up skin interstitial fluid upon skin insertion to form continuous, unblockable, hydrogel conduits from attached patch-type drug reservoirs to the dermal microcirculation. Importantly, such microneedles, which can be fabricated in a wide range of patch sizes and microneedle geometries, can be easily sterilized, resist hole closure while in place, and are removed completely intact from the skin. Delivery of macromolecules is no longer limited to what can be loaded into the microneedles themselves and transdermal drug delivery is now controlled by the crosslink density of the hydrogel system rather than the stratum corneum, while electrically modulated delivery is also a unique feature. This technology has the potential to overcome the limitations of conventional microneedle designs and greatly increase the range of the type of drug that is deliverable transdermally, with ensuing benefits for industry, healthcare providers and, ultimately, patients.
Dissolvable microneedle patches for the delivery of cell-culture-derived influenza vaccine antigens.
Kommareddy Sushma,Baudner Barbara C,Oh Seajin,Kwon Sung-yun,Singh Manmohan,O'Hagan Derek T
Journal of pharmaceutical sciences
Microneedle patches are gaining increasing attention as an alternative approach for the delivery of vaccines. In this study, a licensed seasonal influenza vaccine from 2007 to 2008 was fabricated into dissolvable microneedles using TheraJect's microneedle technology (VaxMat). The tips of the microneedles were made of antigens mixed with trehalose and sodium carboxymethyl cellulose. The patches containing 15 μg per strain of the influenza antigen were characterized extensively to confirm the stability of the antigen following fabrication into microneedles. The presence of excipients and very low concentrations of the vaccine on the microneedle patches made it challenging to characterize using the conventional single radial immunodiffusion analysis. Novel techniques such as capture enzyme-linked immunosorbent assay and enzyme digestion followed by mass spectroscopy were used to characterize the antigens on the microneedle patches. The in vivo studies in mice upon microneedle administration show immunogenicity against monovalent H1N1 at doses 0.1 and 1 μg and trivalent vaccine at a dose of 1 μg. The initial data from the mouse studies is promising and indicates the potential use of microneedle technology for the delivery of influenza vaccine.
Treatment of acute posterior uveitis in a porcine model by injection of triamcinolone acetonide into the suprachoroidal space using microneedles.
Gilger Brian C,Abarca Eva M,Salmon Jacklyn H,Patel Samirkumar
Investigative ophthalmology & visual science
PURPOSE:To evaluate the effect of triamcinolone acetonide (TA) administered into the suprachoroidal space (SCS) using a microneedle and compare it with intravitreal (IVT) TA injections in a porcine model of acute posterior segment inflammation. MATERIALS:An IVT injection of balanced salt solution (BSS) or lipopolysaccharide (LPS) was followed 24 hours later with an injection of 0.2 mg or 2.0 mg of TA into the SCS or IVT. The SCS was accessed using microneedles in a minimally invasive procedure. Ocular inflammatory scores and IOP measurements were collected daily, whereas electroretinography, optical coherence tomography, and wide-field ocular fundus photography was performed on -1, 0, and 3 days after treatment. Aqueous and vitreous humor cell counts and protein levels and histopathology were also compared. RESULTS:Delivery of TA to the SCS using microneedles was simple, effective, and not associated with adverse effects or toxicity. SCS injection of low (0.2 mg) and high doses (2.0 mg) of TA was as effective in reducing acute inflammation in the ocular posterior segment as high-dose IVT injection. Low-dose SCS TA was also effective in reducing inflammation; however, low-dose IVT TA was not. CONCLUSIONS:Results from this study suggest that 0.2 mg and 2.0 mg of SCS TA was as effective in reducing inflammation as 2.0 mg IVT TA injection in a model of acute posterior segment inflammation. There were no adverse effects, increased IOP, or evidence of procedural or drug toxicity following injection of TA into the SCS in porcine eyes.
Evaluation of a minimally invasive system for measuring glucose area under the curve during oral glucose tolerance tests: usefulness of sweat monitoring for precise measurement.
Sakaguchi Kazuhiko,Hirota Yushi,Hashimoto Naoko,Ogawa Wataru,Hamaguchi Tomoya,Matsuo Toshihiro,Miyagawa Jun-ichiro,Namba Mitsuyoshi,Sato Toshiyuki,Okada Seiki,Tomita Koji,Matsuhisa Munehide,Kaneto Hideaki,Kosugi Keisuke,Maegawa Hiroshi,Nakajima Hiromu,Kashiwagi Atsunori
Journal of diabetes science and technology
AIMS:We developed a system for measuring glucose area under the curve (AUC) using minimally invasive interstitial fluid extraction technology (MIET). Sweat contamination during interstitial fluid glucose (IG) extraction affects the accuracy of glucose AUC measurement, because this technology uses extracted sodium ion levels as an internal standard. Therefore, we developed a sweat monitoring patch to reduce this effect and investigated its efficacy in volunteers undergoing oral glucose tolerance tests (OGTTs). MATERIALS AND METHODS:Fifty diabetes mellitus inpatients and 10 healthy subjects undergoing the 75 g OGTT were included. Two sites on the forearm were pretreated with microneedle arrays, then hydrogels for interstitial fluid extraction were placed on the treated sites. Simultaneously, hydrogels for sweat monitoring were placed on untreated sites near the treated sites. Plasma glucose (PG) levels were measured every 30 min for 2 h to calculate reference AUC values. Using MIET, IG AUC was calculated from extracted glucose and sodium ion levels after attachment of the hydrogel for 2 h. RESULTS:Good correlation between IG AUC measurements using MIET and reference AUCs measured using PG levels was confirmed over a wide AUC range (202-610 mg/h/dl) after correction for the sweat-induced error detected by the hydrogel patches on the nonpretreated skin. Strong correlation between IG AUC and peak glucose levels indicates that glucose spikes can be easily detected by this system. CONCLUSION:We confirmed the effectiveness of a sweat monitoring patch for precise AUC measurement using MIET. This novel, easy-to-use system has potential for glucose excursion evaluation in daily clinical practice.
Hydrogel-forming and dissolving microneedles for enhanced delivery of photosensitizers and precursors.
Donnelly Ryan F,Morrow Desmond I J,McCrudden Maelíosa T C,Alkilani Ahlam Zaid,Vicente-Pérez Eva M,O'Mahony Conor,González-Vázquez Patricia,McCarron Paul A,Woolfson A David
Photochemistry and photobiology
We present "one-step application" dissolving and hydrogel-forming microneedle arrays (MN) for enhanced delivery of photosensitizers/precursors. MN (280 μm) prepared from 20% w/w poly(methylvinylether/maelic acid) and cross-linked with glycerol by esterification to form hydrogels upon skin insertion, or allowed to dissolve rapidly in skin, were combined with patches containing 19 mg cm(-2) of 5-aminolevulinic acid (ALA) or meso-tetra (N-methyl-4-pyridyl) porphine tetra tosylate (TMP) for drug delivery. Both MN types were mechanically robust, with compression forces of 20.0 N only causing height reductions of 14%. Application forces as low as 8.0 N per array allowed >95% of the MN in each array type to penetrate excised porcine skin, with the MN penetrating to approximately 220 μm. MN significantly enhanced transdermal delivery of ALA and TMP in vitro, with the hydrogel-forming system comparable with the dissolving system for ALA delivery (approximately 3000 nmol cm(-2) over 6 h), but superior for delivery of the much larger TMP molecule (approximately 14 nmol cm(-2) over 24 h, compared to 0.15 nmol cm(-2)). As this technology clearly has potential in enhanced photodynamic therapy of neoplastic skin lesions, we are currently planning animal studies, to be followed by preliminary human evaluations. GMP manufacturing scale-up is ongoing.
Nanocomposite-strengthened dissolving microneedles for improved transdermal delivery to human skin.
Yan Li,Raphael Anthony P,Zhu Xiaoyue,Wang Beilei,Chen Wei,Tang Tao,Deng Yan,Sant Himanshu J,Zhu Guangyu,Choy Kwong Wai,Gale Bruce K,Prow Tarl W,Chen Xianfeng
Advanced healthcare materials
Delivery of drugs and biomolecules into skin has significant advantages. To achieve this, herein, a nanomaterial-strengthened dissolving microneedle patch for transdermal delivery is reported. The patch comprises thousands of microneedles, which are composed of dissolving polymers, nanomaterials, and drug/biomolecules in their interior. With the addition of nanomaterials, the mechanical property of generally weak dissolving polymers can be dramatically improved without sacrificing dissolution rate within skin. In this experiments, layered double hydroxides (LDH) nanoparticles are incorporated into sodium carboxymethylcellulose (CMC) to form a nanocomposite. The results show that, by adding 5 wt% of LDH nanoparticles into CMC, the mechanical strength significantly increased. Small and densely packed CMC-LDH microneedles penetrate human and pig skin more reliably than pure CMC ones and attractively the nanocomposite-strengthened microneedles dissolve in skin and release payload within only 1 min. Finally, the application of using the nanocomposite-strengthened microneedle arrays is tested for in vivo vaccine delivery and the results show that significantly stronger antibody response could be induced when compared with subcutaneous injection. These data suggest that nanomaterials could be useful for fabricating densely packed and small polymer microneedles that have robust mechanical properties and rapid dissolution rates and therefore potential use in clinical applications.
Automicroneedle therapy system combined with topical tretinoin shows better regenerative effects compared with each individual treatment.
Kim J H,Park H Y,Jung M,Choi E H
Clinical and experimental dermatology
BACKGROUND:Regenerative therapy is a relatively new dermatological field. However, the currently available topical agents are unsuitable for transdermal drug delivery because of their high molecular weight and low liposolubility. Therefore, a more effective transdermal drug delivery system is needed in order to achieve better therapeutic effects with these agents. A recently introduced microneedle therapy system (MTS), which is a mechanical method for making minute holes in the skin, improves transdermal delivery. A recently developed refinement of this technique, the automicroneedle therapy system (AMTS), has several advantages over the traditional MTS, as it can achieve consistent results because of its automatic punching method. AIM:To evaluate the cutaneous effects of an AMTS in combination with topical tretinoin. METHODS:Twelve hairless mice were divided into two groups, and the dorsal skin of each mouse was marked down the centre. The first group was treated with the AMTS plus 0.025% tretinoin on one side of the back, and with 0.025% tretinoin only on the other side. The other group was treated with the AMTS and vehicle on one side, while the other side was left untreated. The effects on cutaneous regeneration and the treatment side-effects were evaluated by functional assessment including transepidermal water loss and skin hydration, and by histopathology including epidermal and dermal thickness, and density of collagen fibres. Western blotting and real-time reverse transcriptase PCR were also performed to determine protein and mRNA expression of procollagen type 1 and matrix metalloproteinase-13. RESULTS:Compared with the individual treatments (the AMTS alone or tretinoin alone) the combination of tretinoin plus the AMTS produced greater dermal regeneration as a result of increased proliferation of collagen fibres. This combination therapy did not result in treatment-related adverse effects. CONCLUSIONS:An AMTS combined with topical tretinoin is a safe and effective method for skin regeneration, which works by increasing collagen production, and might be a new therapeutic option for regenerative therapy.
Evaluation of postprandial glucose excursion using a novel minimally invasive glucose area-under-the-curve monitoring system.
Kuranuki Sachi,Sato Toshiyuki,Okada Seiki,Hosoya Samiko,Seko Akinobu,Sugihara Kaya,Nakamura Teiji
Journal of healthcare engineering
OBJECTIVE:To develop a minimally invasive interstitial fluid extraction technology (MIET) to monitor postprandial glucose area under the curve (AUC) without blood sampling, we evaluated the accuracy of glucose AUC measured by MIET and compared with that by blood sampling after food intake. METHODS:Interstitial fluid glucose AUC (IG-AUC) following consumption of 6 different types of foods was measured by MIET. MIET consisted of stamping microneedle arrays, placing hydrogel patches on the areas, and calculating IG-AUC based on glucose levels in the hydrogels. Glycemic index (GI) was determined using IG-AUC and reference AUC measured by blood sampling. RESULTS:IG-AUC strongly correlated with reference AUC (R = 0.91), and GI determined using IG-AUC showed good correlation with that determined by reference AUC (R = 0.88). CONCLUSIONS:IG-AUC obtained by MIET can accurately predict the postprandial glucose excursion without blood sampling. In addition, feasibility of GI measurement by MIET was confirmed.
[From basic principles to clinical applications on transcutaneous vaccine].
Yakugaku zasshi : Journal of the Pharmaceutical Society of Japan
The recent vigorous transnational migration of people and materials reflecting the development of transportation facilities, changes in social structure, and war disasters has increased the global spread of emerging and re-emerging infectious diseases. Vaccine, which is the major fundamental prophylaxis against infectious diseases, has greatly contributed to the maintenance and improvement of human health worldwide. However, the disadvantages of conventional injection systems hamper the speedy mass-vaccination and the global distribution of vaccines. Transcutaneous immunization systems, which are easy-to-use and low-invasive methods of vaccination, have the potential to overcome certain issues associated with injectable vaccinations. In this review, we provide an outline of recent trends in the development of techniques for the transcutaneous delivery of vaccine antigens. We also introduce basic and clinical research involving our transcutaneous immunization systems that incorporate self-dissolving microneedle patch.
Cowhage can induce itch in the atopic dog.
Olivry Thierry,Bizikova Petra,Paps Judy S,Dunston Stan,Lerner Ethan A,Yosipovitch Gil
Itch is a cardinal symptom of atopic dermatitis in humans and dogs. Until now, experimental induction of itch in dogs has proven difficult. The objectives of this study were to determine whether protease-rich spicules, protein extracts and the protease mucunain of the tropical legume cowhage provoked itch and inflammation when rubbed onto canine skin. Native spicules variably induced itch manifestations in about half of the dogs, while challenges with protease-deactivated spicules remained negative. The epicutaneous application of cowhage extract and mucunain after microneedle roller usage also induced pruritus and inflammation. Importantly, there was an interindividual inconsistency in pruritus and inflammation induction and also marked differences in pruritus intensity after challenge. In conclusion, cowhage spicules, protein-rich extracts and mucunain can all induce pruritus and inflammation in dogs as in other species, but the inconsistency of provocation is currently a limitation of this challenge type for future studies of pruritus in dogs.
Array of Biodegradable Microraftsfor Isolation and Implantation of Living, Adherent Cells.
Wang Yuli,Phillips Colleen N,Herrera Gabriela S,Sims Christopher E,Yeh Jen Jen,Allbritton Nancy L
A new strategy for efficient sorting and implantation of viable adherent cells into animals is described. An array of biodegradable micro-structures (microrafts) was fabricated using a polydimethylsiloxane substrate for micromolding poly(lactic-co-glycolic acid) (PLGA). Screening various forms of PLGA determined that the suitability of PLGA for microraft manufacture, biocompatibility and degradation was dependent on molecular weight and lactic/glycolic ratio. Cells plated on the array selectively attached to the microrafts and could be identified by their fluorescence, morphology or other criteria. The cells were efficiently dislodged and collected from the array using a microneedle device. The platform was used to isolate specific cells from a mixed population establishing the ability to sort target cells for direct implantation. As a proof of concept, fluorescently conjugated microrafts carrying tumor cells stably expressing luciferase were isolated from an array and implanted subcutaneously into mice. bio-luminescence imaging confirmed the growth of a tumor in the recipient animals. Imaging of tissue sections from the tumors demonstrated degradation of the implanted microrafts. The process is a new strategy for isolating and delivering a small number of adherent cells for animal implantation with potential applications in tissue repair, tumor induction, differentiation of stem cells and other biomedical research.
Safety evaluation of topical valproate application.
Choi Sun Young,Seop Song Yi,Hyun Moo Yeol,Yoo Kwang Ho,Kim Beom Joon,Kim Myeung Nam,Cho Jae-We
The potential role of topical valproate (VPA) in hair regrowth has been recently suggested. However, safety reports of VPA as a topical formulation are lacking. Therefore, in the present study, we investigated whether VPA causes skin irritation in humans. We first performed a cell viability test and showed that VPA did not exhibit toxicity toward HaCaT keratinocytes, fibroblasts, and RBL-3H mast cells. We then performed clinical patch test and skin irritation test through transdermal drug delivery with the help of microneedle rollers. No significant findings were obtained in the clinical patch test. In the skin irritation test, only 1 patient showed erythema at 1 hr, but the irritation reaction faded away within a few hours. Erythema and edema were not observed at 24 hr. We concluded that VPA has minimal potential to elicit skin irritation. Therefore, we consider that VPA can safely be applied to human skin.
Polymer multilayer tattooing for enhanced DNA vaccination.
DeMuth Peter C,Min Younjin,Huang Bonnie,Kramer Joshua A,Miller Andrew D,Barouch Dan H,Hammond Paula T,Irvine Darrell J
DNA vaccines have many potential benefits but have failed to generate robust immune responses in humans. Recently, methods such as in vivo electroporation have demonstrated improved performance, but an optimal strategy for safe, reproducible, and pain-free DNA vaccination remains elusive. Here we report an approach for rapid implantation of vaccine-loaded polymer films carrying DNA, immune-stimulatory RNA, and biodegradable polycations into the immune-cell-rich epidermis, using microneedles coated with releasable polyelectrolyte multilayers. Films transferred into the skin following brief microneedle application promoted local transfection and controlled the persistence of DNA and adjuvants in the skin from days to weeks, with kinetics determined by the film composition. These 'multilayer tattoo' DNA vaccines induced immune responses against a model HIV antigen comparable to electroporation in mice, enhanced memory T-cell generation, and elicited 140-fold higher gene expression in non-human primate skin than intradermal DNA injection, indicating the potential of this strategy for enhancing DNA vaccination.
Transdermal delivery: product and patent update.
Gupta Himanshu,Babu R J
Recent patents on drug delivery & formulation
Transdermal drug delivery is an attractive alternative to the oral and parenteral drug delivery. Drugs which are prone to first-pass metabolism can be delivered easily in small doses with sustained blood levels through this method. An update to available products along with a review of clinical trials and patents are discussed in this study. In this review, we have compiled 16 drugs, i.e. Buprenorphine, Clonidine, Estradiol, Fentanyl, Granisetron, Lidocaine, Methylphenidate, Nicotine, Nitroglycerin, Oxybutynin, Rivastigmine, Rotigotine, Scopolamine, Selegiline, Testosterone, Influenza virus vaccine (Microneedle) and covering about 22 marketed products on the transdermal system. We present instrumental information on them along with the compilation of current clinical trials on transdermal systems. We summarize the contents of patents granted in last 5 years under different pharmacological categories. This article serves, accordingly as a source of available information focused on transdermal drug delivery research.
Polymeric nanoparticles-based topical delivery systems for the treatment of dermatological diseases.
Zhang Zheng,Tsai Pei-Chin,Ramezanli Tannaz,Michniak-Kohn Bozena B
Wiley interdisciplinary reviews. Nanomedicine and nanobiotechnology
Human skin not only functions as a permeation barrier (mainly because of the stratum corneum layer) but also provides a unique delivery pathway for therapeutic and other active agents. These compounds penetrate via intercellular, intracellular, and transappendageal routes, resulting in topical delivery (into skin strata) and transdermal delivery (to subcutaneous tissues and into the systemic circulation). Passive and active permeation enhancement methods have been widely applied to increase the cutaneous penetration. The pathology, pathogenesis, and topical treatment approaches of dermatological diseases, such as psoriasis, contact dermatitis, and skin cancer, are then discussed. Recent literature has demonstrated that nanoparticles-based topical delivery systems can be successful in treating these skin conditions. The studies are reviewed starting with the nanoparticles based on natural polymers especially chitosan, followed by those made of synthetic, degradable (aliphatic polyesters), and nondegradable (polyacrylates) polymers; emphasis is given to nanospheres made of polymers derived from naturally occurring metabolites, the tyrosine-derived nanospheres (TyroSpheres™). In summary, the nanoparticles-based topical delivery systems combine the advantages of both the nanosized drug carriers and the topical approach, and are promising for the treatment of skin diseases. For the perspectives, the penetration of ultra-small nanoparticles (size smaller than 40 nm) into skin strata, the targeted delivery of the encapsulated drugs to hair follicle stem cells, and the combination of nanoparticles and microneedle array technologies for special applications such as vaccine delivery are discussed.
Potential of biodegradable microneedles as a transdermal delivery vehicle for lidocaine.
Nayak Atul,Das Diganta Bhusan
There has been an increasing interest in applying biotechnology in formulating and characterising new and innovative drug delivery methods, e.g., drug-loaded biodegradable microneedles within the area of transdermal delivery technology. Recently, microneedles have been proposed for use in pain management, e.g., post-operative pain management through delivery of a local anaesthetic, namely, lidocaine. Lidocaine is a fairly common, marketed prescription-based, local anaesthetic pharmaceutical, applied for relieving localised pain and lidocaine-loaded microneedles have been explored. The purpose of this review is to evaluate the properties of biodegradable polymers that may allow the preparation of microneedle systems, methods of preparing them and pharmacokinetic conditions in considering the potential use of lidocaine for delivery through the skin.
Bone marrow stromal cells inhibit caspase-12 expression in rats with spinal cord injury.
Liu Wei,Ding Yueming,Zhang Xiaoming,Wang Linlin
Experimental and therapeutic medicine
The mechanisms underlying the potentially beneficial effect of bone marrow stem cells (BMSCs) on spinal cord injury (SCI) are unknown. Therefore, the aim of the present study was to explore the protective effect of BMSCs in rats with SCI. A total of 45 adult male Sprague-Dawley rats were randomly divided into three groups; the SCI group (n=15), the BMSC group (n=15) and the sham-operation group (n=15). In the SCI and BMSC treatment groups, a modified Allen's weight-drop technique was used to induce SCI. The BMSC treatment group received an injection of BMSCs using a microneedle into the epicenter of the spinal cord 24 h after injury. Rats in the sham-operation group were not subjected to SCI; however, the corresponding vertebral laminae were removed. Seven days after transplantation, a rapid recovery was observed in the Basso, Beattie and Bresnahan (BBB) scores of the BMSC treatment group, whereas the BBB scores in the SCI group remained low (P<0.05). Caspase-12 expression in the SCI group was increased compared with that in the sham-operation group, whereas caspase-12 expression was attenuated 24 h after transplantation in the BMSC treatment group (P<0.05). In conclusion, the transplantation of BMSCs may improve locomotor function and attenuate caspase-12 expression following SCI. Therefore, it is likely to be an effective strategy for preventing severe injury of the spinal cord.
Improved percutaneous delivery of ketoprofen using combined application of nanocarriers and silicon microneedles.
Vučen Sonja R,Vuleta Gordana,Crean Abina M,Moore Anne C,Ignjatović Nenad,Uskoković Dragan
The Journal of pharmacy and pharmacology
OBJECTIVES:The aim of our study was to evaluate the effect of designing ketoprofen-loaded nanosized spheres and combining them with solid silicon microneedles for enhanced and sustained percutaneous drug delivery. METHODS:Ketoprofen-loaded nanoparticles (KET-NP) were designed by modified solvent displacement method, using poly (D, L-lactic acid) (PDLLA). All prepared nanoparticles were characterised with regard to their particle size distribution, morphology, surface properties, thermal behaviour, drug content, drug release and stability. In-vitro skin permeation studies were conducted on Franz-type diffusion cells using porcine skin treated with ImmuPatch silicon microneedles (Tyndall Nation Institute, Cork, Ireland). KEY FINDINGS:The study showed that uniform nanospheres were prepared with high encapsulation efficiency and retained stable for 2 months. After an initial burst release, the PDLLA nanoparticles were capable of sustaining and controlling ketoprofen release that followed Korsmeyer-Peppas kinetics. An enhanced flux of ketoprofen was observed in the skin treated with silicon microneedles over a prolonged period of time. CONCLUSIONS:Following application of silicon microneedle arrays, KET-NP were able to enhance ketoprofen flux and supply the porcine skin with drug over a prolonged (24 h) period of time. Our findings indicate that the delivery strategy described here could be used for the further development of effective and painless administration systems for sustained percutaneous delivery of ketoprofen.
Usefulness of a novel system for measuring glucose area under the curve while screening for glucose intolerance in outpatients.
Sakamoto Kenya,Kubo Fumiyo,Yoshiuchi Kazutomi,Ono Akemi,Sato Toshiyuki,Tomita Koji,Sakaguchi Kazuhiko,Matsuhisa Munehide,Kaneto Hideaki,Maegawa Hiroshi,Nakajima Hiromu,Kashiwagi Atsunori,Kosugi Keisuke
Journal of diabetes investigation
AIMS/INTRODUCTION:To realize the effectiveness of a novel system for measuring glucose area under the curve (AUC) using minimally invasive interstitial fluid extraction technology (MIET), outpatients undergoing oral glucose tolerance tests (OGTT) were investigated for the efficacy of screening for glucose intolerance using this system. MATERIALS AND METHODS:Fifty outpatients scheduled to undergo a 75-g OGTT for medical reasons were recruited to the study. An area of skin on the forearm was pretreated with microneedle arrays before the application of hydrogels for interstitial fluid extraction. Plasma glucose (PG) levels were measured every 30 min for 2 h to calculate reference (actual) AUC. The AUC was predicted by MIET on the basis of glucose extracted by the hydrogel using sodium ion levels as the internal standard. RESULTS:Good correlation between MIET-predicted and reference AUCs obtained using PG levels was confirmed for a wide AUC range. By introducing a threshold level for AUC to separate glucose intolerance with peak glucose ≥180 mg/dL from normal glucose tolerance, the system was demonstrated to provide better screening accuracy compared with conventional methods that use HbA1c and fasting PG levels. The results of a questionnaire-based survey administered to the subjects suggested that this system was readily accepted by the majority as a painless monitoring method. CONCLUSIONS:The findings suggest that our glucose AUC measurement system using MIET would be useful for screening of glucose intolerance. In the future, this system may prove to be a useful aid as a screen for glucose intolerance before performing an OGTT for diagnosis.
Development of vertical SU-8 microneedles for transdermal drug delivery by double drawing lithography technology.
Xiang Zhuolin,Wang Hao,Pant Aakanksha,Pastorin Giorgia,Lee Chengkuo
Polymer-based microneedles have drawn much attention in transdermal drug delivery resulting from their flexibility and biocompatibility. Traditional fabrication approaches are usually time-consuming and expensive. In this study, we developed a new double drawing lithography technology to make biocompatible SU-8 microneedles for transdermal drug delivery applications. These microneedles are strong enough to stand force from both vertical direction and planar direction during penetration. They can be used to penetrate into the skin easily and deliver drugs to the tissues under it. By controlling the delivery speed lower than 2 μl/min per single microneedle, the delivery rate can be as high as 71%.
Nanotechnology: emerging tools for biology and medicine.
Wong Ian Y,Bhatia Sangeeta N,Toner Mehmet
Genes & development
Historically, biomedical research has been based on two paradigms. First, measurements of biological behaviors have been based on bulk assays that average over large populations. Second, these behaviors have then been crudely perturbed by systemic administration of therapeutic treatments. Nanotechnology has the potential to transform these paradigms by enabling exquisite structures comparable in size with biomolecules as well as unprecedented chemical and physical functionality at small length scales. Here, we review nanotechnology-based approaches for precisely measuring and perturbing living systems. Remarkably, nanotechnology can be used to characterize single molecules or cells at extraordinarily high throughput and deliver therapeutic payloads to specific locations as well as exhibit dynamic biomimetic behavior. These advances enable multimodal interfaces that may yield unexpected insights into systems biology as well as new therapeutic strategies for personalized medicine.
Intanza (®) 9 µg intradermal seasonal influenza vaccine for adults 18 to 59 years of age.
Leroux-Roels Isabel,Weber Françoise
Human vaccines & immunotherapeutics
Seasonal influenza in healthy working-age adults accounts for a substantial part of the socioeconomic burden of this disease. Intanza® 9 µg (sanofi pasteur) is a microneedle-delivered intradermal trivalent inactivated influenza vaccine approved in 2009 for the prevention of seasonal influenza in adults 18 to 59 years of age. The microneedle system reliably and reproducibly delivers the vaccine to the dermis. Clinical studies show that Intanza 9 µg is as immunogenic and as well tolerated in working-age adults as a reference intramuscular trivalent inactivated vaccine. Local reactions to Intanza 9 µg, mainly erythema, are transient, mostly mild or moderate, and do not affect acceptability. Intanza 9 µg is considered satisfactory by at least 95% of both vaccinees and prescribers, especially because of the short needle and rapid administration. Because Intanza® 9 µg offers an alternative to intramuscular vaccines, it might help increase influenza vaccine coverage rates.
Particle based vaccine formulations for transcutaneous immunization.
Mittal Ankit,Raber Anne S,Lehr Claus-Michael,Hansen Steffi
Human vaccines & immunotherapeutics
Vaccine formulations on the basis of nano- (NP) or microparticles (MP) can solve issues with stabilization, controlled release, and poor immunogenicity of antigens. Likewise transcutaneous immunization (TCI) promises superior immunogenicity as well as the advantages of needle-free application compared with conventional intramuscular injections. Thus the combination of both strategies seems to be a very valuable approach. However, until now TCI using particle based vaccine formulations has made no impact on medical practice. One of the main difficulties is that NPs and MPs cannot penetrate the skin to an extent that would allow the application of the required dose of antigen. This is due to the formidable stratum corneum (SC) barrier, the limited amount of antigen in the formulation and often an insufficient immunogenicity. A multitude of strategies are currently under investigation to overcome these issues. We highlight selected methods presenting a spectrum of solutions ranging from transfollicular delivery, to devices disrupting the SC barrier and the combination of particle based vaccines with adjuvants discussing their advantages and shortcomings. Some of these are currently at an experimental state while others are already in clinical testing. All methods have been shown to be capable of transcutaneous antigen delivery.
Stability of whole inactivated influenza virus vaccine during coating onto metal microneedles.
Choi Hyo-Jick,Bondy Brian J,Yoo Dae-Goon,Compans Richard W,Kang Sang-Moo,Prausnitz Mark R
Journal of controlled release : official journal of the Controlled Release Society
Immunization using a microneedle patch coated with vaccine offers the promise of simplified vaccination logistics and increased vaccine immunogenicity. This study examined the stability of influenza vaccine during the microneedle coating process, with a focus on the role of coating formulation excipients. Thick, uniform coatings were obtained using coating formulations containing a viscosity enhancer and surfactant, but these formulations retained little functional vaccine hemagglutinin (HA) activity after coating. Vaccine coating in a trehalose-only formulation retained about 40-50% of vaccine activity, which is a significant improvement. The partial viral activity loss observed in the trehalose-only formulation was hypothesized to come from osmotic pressure-induced vaccine destabilization. We found that inclusion of a viscosity enhancer, carboxymethyl cellulose, overcame this effect and retained full vaccine activity on both washed and plasma-cleaned titanium surfaces. The addition of polymeric surfactant, Lutrol® micro 68, to the trehalose formulation generated phase transformations of the vaccine coating, such as crystallization and phase separation, which was correlated to additional vaccine activity loss, especially when coating on hydrophilic, plasma-cleaned titanium. Again, the addition of a viscosity enhancer suppressed the surfactant-induced phase transformations during drying, which was confirmed by in vivo assessment of antibody response and survival rate after immunization in mice. We conclude that trehalose and a viscosity enhancer are beneficial coating excipients, but the inclusion of surfactant is detrimental to vaccine stability.
Hollow microneedles for intradermal injection fabricated by sacrificial micromolding and selective electrodeposition.
Norman James J,Choi Seong-O,Tong Nhien T,Aiyar Avishek R,Patel Samirkumar R,Prausnitz Mark R,Allen Mark G
Limitations with standard intradermal injections have created a clinical need for an alternative, low-cost injection device. In this study, we designed a hollow metal microneedle for reliable intradermal injection and developed a high-throughput micromolding process to produce metal microneedles with complex geometries. To fabricate the microneedles, we laser-ablated a 70 μm × 70 μm square cavity near the tip of poly(lactic acid) (PLA) microneedles. The master structure was a template for multiple micromolded poly(lactic acid-co-glycolic acid) (PLGA) replicas. Each replica was sputtered with a gold seed layer with minimal gold deposited in the cavity due to masking effects. In this way, nickel was electrodeposited selectively outside of the cavity, after which the polymer replica was dissolved to produce a hollow metal microneedle. Force-displacement tests showed the microneedles, with 12 μm thick electrodeposition, could penetrate skin with an insertion force 9 times less than their axial failure force. We injected fluid with the microneedles into pig skin in vitro and hairless guinea pig skin in vivo. The injections targeted 90 % of the material within the skin with minimal leakage onto the skin surface. We conclude that hollow microneedles made by this simple microfabrication method can achieve targeted intradermal injection.
BioMEMS in drug delivery.
Advanced drug delivery reviews
The drive to design micro-scale medical devices which can be reliably and uniformly mass produced has prompted many researchers to adapt processing technologies from the semiconductor industry. By operating at a much smaller length scale, the resulting biologically-oriented microelectromechanical systems (BioMEMS) provide many opportunities for improved drug delivery: Low-dose vaccinations and painless transdermal drug delivery are possible through precisely engineered microneedles which pierce the skin's barrier layer without reaching the nerves. Low-power, low-volume BioMEMS pumps and reservoirs can be implanted where conventional pumping systems cannot. Drug formulations with geometrically complex, extremely uniform micro- and nano-particles are formed through micromolding or with microfluidic devices. This review describes these BioMEMS technologies and discusses their current state of implementation. As these technologies continue to develop and capitalize on their simpler integration with other MEMS-based systems such as computer controls and telemetry, BioMEMS' impact on the field of drug delivery will continue to increase.
Background free imaging of upconversion nanoparticle distribution in human skin.
Song Zhen,Anissimov Yuri G,Zhao Jiangbo,Nechaev Andrei V,Nadort Annemarie,Jin Dayong,Prow Tarl W,Roberts Michael S,Zvyagin Andrei V
Journal of biomedical optics
Widespread applications of nanotechnology materials have raised safety concerns due to their possible penetration through skin and concomitant uptake in the organism. This calls for systematic study of nanoparticle transport kinetics in skin, where high-resolution optical imaging approaches are often preferred. We report on application of emerging luminescence nanomaterial, called upconversion nanoparticles (UCNPs), to optical imaging in skin that results in complete suppression of background due to the excitation light back-scattering and biological tissue autofluorescence. Freshly excised intact and microneedle-treated human skin samples were topically coated with oil formulation of UCNPs and optically imaged. In the first case, 8- and 32-nm UCNPs stayed at the topmost layer of the intact skin, stratum corneum. In the second case, 8-nm nanoparticles were found localized at indentations made by the microneedle spreading in dermis very slowly (estimated diffusion coefficient, D(np) = 3-7 × 10(-12) cm(2) · s(-1)). The maximum possible UCNP-imaging contrast was attained by suppressing the background level to that of the electronic noise, which was estimated to be superior in comparison with the existing optical labels.
Advanced deep reactive-ion etching technology for hollow microneedles for transdermal blood sampling and drug delivery.
Liu Yufei,Eng Pay F,Guy Owen J,Roberts Kerry,Ashraf Huma,Knight Nick
Using an SPTS Technologies Ltd. Pegasus deep reactive-ion etching (DRIE) system, an advanced two-step etching process has been developed for hollow microneedles in applications of transdermal blood sampling and drug delivery. Because of the different etching requirements of both narrow deep hollow and large open cavity, hollow etch and cavity etch steps have been achieved separately. This novel two-step etching process is assisted with a bi-layer etching mask. Results show that the etch rate of silicon during this hollow etch step was about 7.5 microm/min and the etch rate of silicon during this cavity etch step was about 8-10 microm/min, using the coil plasma etching power between 2.0 and 2.8 kW. Especially for the microneedle bores etch, the deeper it etched, the slower the etch rate was. The microneedle bores have successfully been obtained 75-150 microm in inner diametre and 700-1000 microm long with high aspect ratio DRIE, meanwhile, the vertical sidewall structures have been achieved with the high etch load exposed area over 70% for the cavity etch step.
Early circulating biomarker detection using a wearable microprojection array skin patch.
Coffey Jacob W,Corrie Simon R,Kendall Mark A F
Microprojection array (MPA) skin patches selectively capture circulating biomarkers from the dermal layers of the skin, avoiding the need to extract, handle or process blood. Here we investigate the effect of improving biomarker capture in vivo on MPA detection of a model biomarker (antigen-specific-IgG raised in response to Fluvax vaccine) in a murine model. First, we investigate targeting MPA penetration to biomarker rich regions of the skin by varying MPA penetration depth. We observed a 4-fold increase in biomarker capture from predominantly epidermal to deep dermal penetration (27 ± 9 μm-153 ± 30 μm penetration range). We then study the kinetics of biomarker capture by varying the contact time with skin from rapid application (less than 20 min) to long term application (up to 24 h) with a wearable MPA patch. We observed MPAs reproducibly captured detectable amounts of our model biomarker after 10 min application and a greater than 6-fold increase in capture was observed up to 6 h application. Combining the effect of penetration depth and application time we obtained comparable early detection (after vaccination) of our model biomarker as a standard enzyme-linked immunosorbent assay (ELISA). We expect that integration of these devices with existing detection technologies has potential advantages in rapid diagnostic tests, particularly in cases where laboratory-based sample collection and processing is not available.
Development of vertical SU-8 microtubes integrated with dissolvable tips for transdermal drug delivery.
Xiang Zhuolin,Wang Hao,Pant Aakanksha,Pastorin Giorgia,Lee Chengkuo
Polymer-based microneedles have drawn much attention in the transdermal drug delivery resulting from their flexibility and biocompatibility. Traditional fabrication approach deploys various kinds of molds to create sharp tips at the end of needles for the penetration purpose. This approach is usually time-consuming and expensive. In this study, we developed an innovative fabrication process to make biocompatible SU-8 microtubes integrated with biodissolvable maltose tips as novel microneedles for the transdermal drug delivery applications. These microneedles can easily penetrate the skin's outer barrier represented by the stratum corneum (SC) layer. The drug delivery device of mironeedles array with 1000 μm spacing between adjacent microneedles is proven to be able to penetrate porcine cadaver skins successfully. The maximum loading force on the individual microneedle can be as large as 7.36 ± 0.48N. After 9 min of the penetration, all the maltose tips are dissolved in the tissue. Drugs can be further delivered via these open biocompatible SU-8 microtubes in a continuous flow manner. The permeation patterns caused by the solution containing Rhodamine 110 at different depths from skin surface were characterized via a confocal microscope. It shows successful implementation of the microneedle function for fabricated devices.
Controlled delivery of ropinirole hydrochloride through skin using modulated iontophoresis and microneedles.
Singh Neha D,Banga Ajay K
Journal of drug targeting
The objective of this study was to investigate the effect of modulated current application using iontophoresis- and microneedle-mediated delivery on transdermal permeation of ropinirole hydrochloride. AdminPatch® microneedles and microchannels formed by them were characterized by scanning electron microscopy, dye staining and confocal microscopy. In vitro permeation studies were carried out using Franz diffusion cells, and skin extraction was used to quantify drug in underlying skin. Effect of microneedle pore density and ions in donor formulation was studied. Active enhancement techniques, continuous iontophoresis (74.13 ± 2.20 µg/cm(2)) and microneedles (66.97 ± 10.39 µg/cm(2)), significantly increased the permeation of drug with respect to passive delivery (8.25 ± 2.41 µg/cm(2)). Modulated iontophoresis could control the amount of drug delivered at a given time point with the highest flux being 5.12 ± 1.70 µg/cm(2)/h (5-7 h) and 5.99 ± 0.81 µg/cm(2)/h (20-22 h). Combination of modulated iontophoresis and microneedles (46.50 ± 6.46 µg/cm(2)) showed significantly higher delivery of ropinirole hydrochloride compared to modulated iontophoresis alone (84.91 ± 9.21 µg/cm(2)). Modulated iontophoresis can help in maintaining precise control over ropinirole hydrochloride delivery for dose titration in Parkinson's disease therapy and deliver therapeutic amounts over a suitable patch area and time.
Polymer microneedles for transdermal drug delivery.
Lee Jeong Woo,Han Mee-Ree,Park Jung-Hwan
Journal of drug targeting
A microneedle system has been developed to deliver chemical and biological agents through the stratum corneum, which is the main barrier to drug delivery. Recently, microneedles have been fabricated from various kinds of polymers, including biocompatible polymer, biodegradable polymer, and water-soluble polymer. Polymer microneedles offer the benefits of ease of fabrication, cost-effectiveness, and mass production, as well as controlled drug release using the water solubility and degradation properties of polymer. In this review, the key features of polymer microneedles are discussed, including fabrication, materials, mechanical properties, drug delivery properties, and applications. Polymer microneedles provide a promising method for transdermal drug delivery by utilizing various physical and chemical properties of polymer.
Microneedles for intradermal and transdermal drug delivery.
Tuan-Mahmood Tuan-Mazlelaa,McCrudden Maelíosa T C,Torrisi Barbara M,McAlister Emma,Garland Martin J,Singh Thakur Raghu Raj,Donnelly Ryan F
European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences
The formidable barrier properties of the uppermost layer of the skin, the stratum corneum, impose significant limitations for successful systemic delivery of broad range of therapeutic molecules particularly macromolecules and genetic material. Microneedle (MN) has been proposed as a strategy to breach the stratum corneum barrier function in order to facilitate effective transport of molecules across the skin. This strategy involves use of micron sized needles fabricated of different materials and geometries to create transient aqueous conduits across the skin. MN, alone or with other enhancing strategies, has been demonstrated to dramatically enhance the skin permeability of numerous therapeutic molecules including biopharmaceuticals either in vitro, ex vivo or in vivo experiments. This suggested the promising use of MN technology for various possible clinical applications such as insulin delivery, transcutaneous immunisations and cutaneous gene delivery. MN has been proved as minimally invasive and painless in human subjects. This review article focuses on recent and future developments for MN technology including the latest type of MN design, challenges and strategies in MNs development as well as potential safety aspects based on comprehensive literature review pertaining to MN studies to date.
Minimally invasive transdermal delivery of iron-dextran.
Juluri Abhishek,Modepalli Naresh,Jo Seongbong,Repka Michael A,Shivakumar H Nanjappa,Murthy S Narasimha
Journal of pharmaceutical sciences
Iron deficiency is one of the most prevalent and serious health issues among people all over the world. Iron-dextran (ID) colloidal solution is one among the very few US Food and Drug Administration (FDA)-approved iron sources for parenteral administration of iron. Parenteral route does not allow frequent administration because of its invasiveness and other associated complications. The main aim of this project was to investigate the plausibility of transdermal delivery of ID facilitated by microneedles, as an alternative to parenteral iron therapy. In vitro permeation studies were carried out using freshly excised hairless rat abdominal skin in a Franz diffusion apparatus. Iron repletion studies were carried out in hairless anemic rat model. The anemic rats were divided into intact skin (control), microneedle pretreated, and intraperitoneal (i.p.) groups depending on the mode of delivery of iron. The hematological parameters were measured intermittently during treatment. There was no improvement in the hematological parameters in case of control group, whereas, in case of microneedle pretreated and i.p. group, there was significant improvement within 2-3 weeks. The results suggest that microneedle-mediated delivery of ID could be developed as a potential treatment method for iron-deficiency anemia.
Transdermal delivery devices: fabrication, mechanics and drug release from silk.
Raja Waseem K,Maccorkle Scott,Diwan Izzuddin M,Abdurrob Abdurrahman,Lu Jessica,Omenetto Fiorenzo G,Kaplan David L
Small (Weinheim an der Bergstrasse, Germany)
Microneedles are a relatively simple, minimally invasive and painless approach to deliver drugs across the skin. However, there remain limitations with this approach because of the materials most commonly utilized for such systems. Silk protein, with tunable and biocompatibility properties, is a useful biomaterial to overcome the current limitations with microneedles. Silk devices preserve drug activity, offer superior mechanical properties and biocompatibility, can be tuned for biodegradability, and can be processed under aqueous, benign conditions. In the present work, the fabrication of dense microneedle arrays from silk with different drug release kinetics is reported. The mechanical properties of the microneedle patches are tuned by post-fabrication treatments or by loading the needles with silk microparticles, to increase capacity and mechanical strength. Drug release is further enhanced by the encapsulation of the drugs in the silk matrix and coating with a thin dissolvable drug layer. The microneedles are used on human cadaver skin and drugs are delivered successfully. The various attributes demonstrated suggest that silk-based microneedle devices can provide significant benefit as a platform material for transdermal drug delivery.
Droplet backside exposure for making slanted SU-8 microneedles.
Kwon Ki Yong,Bi Xiaopeng,Li Wen
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference
This paper presented a droplet backside exposure (DBE) method for making slanted microneedle structures on a flexible polymer substrate. To demonstrate the feasibility of the DBE approach, SU-8 microneedle arrays were fabricated on polydimethylsiloxane (PDMS) substrates. The length of the microneedles was controlled by tuning the volume of the SU-8 droplet, utilizing the wetting barrier phenomenon at a liquid-vapor-hydrophilic surface-hydrophobic surface interface. The experimental results showed excellent repeatability and controllability of the DBE method for microneedle fabrication. Analytical models were also studied to predict the dimensions of the microneedles, which agreed with the experimental data.
A novel method for monolithic fabrication of polymer microneedles on a platform for transdermal drug delivery.
Chaudhuri Buddhadev P,Ceyssens F,Van Hoof C,Puers R
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference
This paper reports on the creation of a novel method for monolithic fabrication of out-of-plane polymer (SU-8) microneedles incorporating sharpness of needle-tips, hollowness of needle lumen as well as a platform on which the microneedles stand orthogonally with the hollow of the needle lumen continuous through the platform. In essence, both the microneedle as well as the platform on which it stands, are made of the same polymer material, rendering the process monolithic. The microneedle tips produced were quite sharp with tip diameters ranging between 5 to 10 µm, needle heights greater than 1 mm and resulting aspect ratio of 40. Further, mechanical tests performed on the fabricated microneedles demonstrate a critical compressive failure load of about 173 mN on average per microneedle, which translates into a safety factor greater than one for skin penetration.
Composite dissolving microneedles for coordinated control of antigen and adjuvant delivery kinetics in transcutaneous vaccination.
Demuth Peter C,Garcia-Beltran Wilfredo F,Ai-Ling Michelle Lim,Hammond Paula T,Irvine Darrell J
Advanced functional materials
Transcutaneous administration has the potential to improve therapeutics delivery, providing an approach that is safer and more convenient than traditional alternatives, while offering the opportunity for improved therapeutic efficacy through sustained/controlled drug release. To this end, we demonstrate a microneedle materials platform for rapid implantation of controlled-release polymer depots into the cutaneous tissue. Arrays of microneedles comprised of drug-loaded poly(lactide--glycolide) (PLGA) microparticles or solid PLGA tips were prepared with a supporting and rapidly water-soluble poly(acrylic acid) (PAA) matrix. Upon application of microneedle patches to the skin of mice, the microneedles perforated the stratum corneum and epidermis. Penetration of the outer skin layers was followed by rapid dissolution of the PAA binder on contact with the interstitial fluid of the epidermis, implanting the microparticles or solid polymer microneedles in the tissue, which were retained following patch removal. These polymer depots remained in the skin for weeks following application and sustained the release of encapsulated cargos for systemic delivery. To show the utility of this approach we demonstrated the ability of these composite microneedle arrays to deliver a subunit vaccine formulation. In comparison to traditional needle-based vaccination, microneedle delivery gave improved cellular immunity and equivalent generation of serum antibodies, suggesting the potential of this approach for vaccine delivery. However, the flexibility of this system should allow for improved therapeutic delivery in a variety of diverse contexts.
Cross-protection by co-immunization with influenza hemagglutinin DNA and inactivated virus vaccine using coated microneedles.
Kim Yeu-Chun,Yoo Dae-Goon,Compans Richard W,Kang Sang-Moo,Prausnitz Mark R
Journal of controlled release : official journal of the Controlled Release Society
The need for annual revaccination against influenza is a burden on the healthcare system, leads to low vaccination rates and makes timely vaccination difficult against pandemic strains, such as during the 2009 H1N1 influenza pandemic. In an effort toward achieving a broadly protective vaccine that provides cross-protection against multiple strains of influenza, this study developed a microneedle patch to co-immunize with A/PR8 influenza hemagglutinin DNA and A/PR8 inactivated virus vaccine. We hypothesize that this dual component vaccination strategy administered to the skin using microneedles will provide cross-protection against other strains of influenza. To test this hypothesis, we developed a novel coating formulation that did not require additional excipients to increase coating solution viscosity by using the DNA vaccine itself to increase viscosity and thereby enable thick coatings of DNA vaccine and inactivated virus vaccine on metal microneedles. Co-immunization in this way not only generated robust antibody responses against A/PR8 influenza but also generated robust heterologous antibody responses against pandemic 2009 H1N1 influenza in mice. Challenge studies showed complete cross-protection against lethal challenge with live pandemic 2009 H1N1 virus. Control experiments using A/PR8 inactivated influenza virus vaccine with placebo DNA coated onto microneedles produced lower antibody titers and provided incomplete protection against challenge. Overall, this is the first study showing DNA solution as a microneedle coating agent and demonstrating cross-protection by co-immunization with inactivated virus and DNA vaccine using coated microneedles.
Pocketed microneedles for rapid delivery of a liquid-state botulinum toxin A formulation into human skin.
Torrisi B M,Zarnitsyn V,Prausnitz M R,Anstey A,Gateley C,Birchall J C,Coulman S A
Journal of controlled release : official journal of the Controlled Release Society
Botulinum toxin A (BT) is used therapeutically for the treatment of primary focal hyperhidrosis, a chronic debilitating condition characterised by over-activity of the eccrine sweat glands. Systemic toxicity concerns require BT to be administered by local injection, which in the case of hyperhidrosis means multiple painful intradermal injections by a skilled clinician at 6-monthly intervals. This study investigates the potential of a liquid-loaded pocketed microneedle device to deliver botulinum toxin A into the human dermis with the aim of reducing patient pain, improving therapeutic targeting and simplifying the administration procedure. Initially, β-galactosidase was employed as a detectable model for BT to (i) visualise liquid loading of the microneedles, (ii) determine residence time of a liquid formulation on the device and (iii) quantify loaded doses. An array of five stainless steel pocketed microneedles was shown to possess sufficient capacity to deliver therapeutic doses of the potent BT protein. Microneedle-mediated intradermal delivery of β-galactosidase and formaldehyde-inactivated botulinum toxoid revealed effective deposition and subsequent diffusion within the dermis. This study is the first to characterise pocketed microneedle delivery of a liquid formulation into human skin and illustrates the potential of such systems for the cutaneous administration of potent proteins such as BT. A clinically appropriate microneedle delivery system for BT could have a significant impact in both the medical and cosmetic industries.
Spatially discrete thermal drawing of biodegradable microneedles for vascular drug delivery.
Choi Chang Kuk,Lee Kang Ju,Youn Young Nam,Jang Eui Hwa,Kim Woong,Min Byung-Kwon,Ryu WonHyoung
European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V
Spatially discrete thermal drawing is introduced as a novel method for the fabrication of biodegradable microneedles with ultra-sharp tip ends. This method provides the enhanced control of microneedle shapes by spatially controlling the temperature of drawn polymer as well as drawing steps and speeds. Particular focus is given on the formation of sharp tip ends of microneedles at the end of thermal drawing. Previous works relied on the fracture of polymer neck by fast drawing that often causes uncontrolled shapes of microneedle tips. Instead, this approach utilizes the surface energy of heated polymer to form ultra-sharp tip ends. We have investigated the effect of such temperature control, drawing speed, and drawing steps in thermal drawing process on the final shape of microneedles using biodegradable polymers. XRD analysis was performed to analyze the effect of thermal cycle on the biodegradable polymer. Load-displacement measurement also showed the dependency of mechanical strengths of microneedles on the microneedle shapes. Ex vivo vascular tissue insertion and drug delivery demonstrated microneedle insertion to tunica media layer of canine aorta and drug distribution in the tissue layer.
Microporation and 'iron'tophoresis for treating iron deficiency anemia.
Modepalli Naresh,Jo Seongbong,Repka Michael A,Murthy S Narasimha
PURPOSE:Iontophoretic mediated transdermal delivery of ferric pyrophosphate (FPP) in combination with microneedle pretreatment was investigated as a potential treatment for iron deficiency anemia (IDA). METHODS:In vitro transdermal delivery studies were performed using hairless rat skin and pharmacodynamic studies were performed in hairless anemic rat model. The hematological and biochemical parameters like hemoglobin, hematocrit and % serum transferrin were monitored in rats at healthy, anemic condition and post treatment. Micropores created by the microneedles were visualized in histological skin sections after staining with hemotoxylin and eosin. The recovery of micropores was investigated in vivo by measuring Transepidermal water loss (TEWL) at different time points. RESULTS:The passive, microneedle and iontophoresis mediated delivery did not lead to significant improvement in hematological and biochemical parameters in anemic rats, when used individually. When iontophoresis (0.15 mA/cm(2) for 4 hours) was combined with microneedle pretreatment (for 2 min), therapeutically adequate amount of FPP was delivered and there was significant recovery of rats from IDA. CONCLUSIONS:Microneedle and iontophoresis mediated delivery of iron via transdermal route could be developed as a potential treatment for IDA. The transdermal controlled delivery of iron could become a potential, safe and effective alternative to parenteral iron therapy.
Fully embeddable chitosan microneedles as a sustained release depot for intradermal vaccination.
Chen Mei-Chin,Huang Shih-Fang,Lai Kuan-Ying,Ling Ming-Hung
This study introduces a microneedle transdermal delivery system, composed of embeddable chitosan microneedles and a poly(L-lactide-co-D,L-lactide) (PLA) supporting array, for complete and sustained delivery of encapsulated antigens to the skin. Chitosan microneedles were mounted to the top of a strong PLA supporting array, providing mechanical strength to fully insert the microneedles into the skin. When inserted into rat skin in vivo, chitosan microneedles successfully separated from the supporting array and were left within the skin for sustained drug delivery without requiring a transdermal patch. The microneedle penetration depth was approximately 600 μm (i.e. the total length of the microneedle), which is beneficial for targeted delivery of antigens to antigen-presenting cells in the epidermis and dermis. To evaluate the utility of chitosan microneedles for intradermal vaccination, ovalbumin (OVA; MW = 44.3 kDa) was used as a model antigen. When the OVA-loaded microneedles were embedded in rat skin in vivo, histological examination showed that the microneedles gradually degraded and prolonged OVA exposure at the insertion sites for up to 14 days. Compared to traditional intramuscular immunization, rats immunized by a single microneedle dose of OVA showed a significantly higher OVA-specific antibody response which lasted for at least 6 weeks. These results suggest that embeddable chitosan microneedles are a promising depot for extended delivery of encapsulated antigens to provide sustained immune stimulation and improve immunogenicity.
Microprecision delivery of oligonucleotides in a 3D tissue model and its characterization using optical imaging.
Luo Zhen,Ye Ting,Ma Yunzhe,Gill Harvinder Singh,Nitin N
Despite significant potential of oligonucleotides (ONs) for therapeutic and diagnostic applications, rapid and widespread intracellular delivery of ONs in cells situated in tissues such as skin, head and neck cavity, and eye has not been achieved. This study was aimed at evaluating the synergistic combination of microneedle (MN) arrays and biochemical approaches for localized intratissue delivery of oligonucleotides in living cells in 3D tissue models. This synergistic combination was based on the ability of MNs to precisely deliver ONs into tissues to achieve widespread distribution, and the ability of biochemical agents (streptolysin O (SLO) and cholesterol conjugation to ONs) to enhance intracellular ON delivery. The results of this study demonstrate that ON probes were uniformly coated on microneedle arrays and were efficiently released from the microneedle surface upon insertion in tissue phantoms. Co-insertion of microneedles coated with ONs and SLO into 3D tissue models resulted in delivery of ONs into both the cytoplasm and nucleus of cells. Within a short incubation time (35 min), ONs were observed both laterally and along the depth of a 3D tissue up to a distance of 500 μm from the microneedle insertion point. Similar widespread intratissue distribution of ONs was achieved upon delivery of ON-cholesterol conjugates. Uniformity of ON delivery in tissues improved with longer incubation times (24 h) postinsertion. Using cholesterol-conjugated ONs, delivery of ON probes was limited to the cytoplasm of cells within a tissue. Finally, delivery of cholesterol-conjugated anti-GFP ON resulted in reduction of GFP expression in HeLa cells. In summary, the results of this study provide a novel approach for efficient intracellular delivery of ONs in tissues.
Skin pretreatment with microneedles prior to pilocarpine iontophoresis increases sweat production.
Wing David,Prausnitz Mark R,Buono Michael J
Clinical physiology and functional imaging
Collection of sweat via pilocarpine iontophoresis is commonly used to diagnose cystic fibrosis (CF), with thousands of tests performed each day. The main source of resistance to the passage of pilocarpine ions to the sweat glands is the electrical resistance of the stratum corneum. It was hypothesized that pretreating the skin with 0·5 mm-long microneedles would significantly decrease this resistance, thus increasing pilocarpine's permeation into the skin. Improved permeation should result in significantly reduced time to sweat initiation, time to collection of a clinically meaningful amount of sweat, and increased total amount of sweat produced in 15 min. Subjects (n = 12) had two 5 cm(2) areas on the forearm measured, marked and randomized to experimental (microneedles + iontophoresis) or control (iontophoresis alone). Microneedle pretreatment was conducted using a 35-needle microneedle stamp in a manner that 20 applications completely covered the 5 cm(2) treatment area. This was repeated five times for a total of 100 applications. Both experimental and control sites were placed under iontophoresis (1·5 mA) for 5 min. Microneedle pretreatment significantly decreased mean skin resistance (260 ± 27 kΩ versus 160 ± 19 kΩ, P = 0·006), while significantly increasing mean sweat rate (0·76 ± 0·35 versus 0·54 ± 0·19 μl cm(2) min(-1) , P = 0·007). No significant difference was found concerning pain (P = 0·059), number of active sweat glands (P = 0·627) or the osmolality of the collected sweat (P = 0·636). The results of this study suggest that microneedle pretreatment prior to pilocarpine iontophoresis significantly increases sweat production. Such results have the potential to improve the methodology currently used to diagnose cystic fibrosis and, more broadly, to administer drugs via the skin.
Nanolayered chemical modification of silicon surfaces with ionizable surface groups for pH-triggered protein adsorption and release: application to microneedles.
van der Maaden Koen,Yu Huixin,Sliedregt Karen,Zwier Raphäel,Leboux Romain,Oguri Masashi,Kros Alexander,Jiskoot Wim,Bouwstra Joke A
Journal of materials chemistry. B
The aim of this work was to develop a nanolayered pH sensitive coating method whereby proteins are coated at a suitable pH on the surface of chemically modified biomedical/bioanalytical microdevices and protein release is triggered by a pH-shift upon contact with the physiological environment. In this work such a coating was developed and was applied onto microneedles. First, the surface of microneedle arrays was modified with basic groups with a surface pK below physiological pH. This modification was a multistep procedure: first the surface was hydroxylated in a piranha mixture, then 3-aminopropyl-triethoxysilane was coupled (yielding a "pH independent" surface with a positive charge over a broad pH range), next 4-pyridinecarboxaldehyde was coupled to the obtained surface amine groups and finally the imine bond was reduced by sodium cyanoborohydride. The obtained pH-sensitive pyridine-modified microneedles were coated with ovalbumin at surface pK > pH > pI of the protein; thus the surface of the microneedles is positively charged and the protein is negatively charged. The coating efficiency of ovalbumin was 95% for the amine-modified (pH independent) and the pyridine-modified (pH sensitive) surfaces, whereas a non-modified surface had a coating efficiency of only 2%. After the protein-coated microneedle arrays were pierced into the skin, having a pH > surface pK of the microneedle arrays, 70% of the protein was released within 1 minute, whereas the protein release from pH independent microneedle arrays was only 5%. In conclusion, we developed a procedure to efficiently coat microneedle arrays with proteins that are released upon piercing into human skin.
The Effects of Geometry on Skin Penetration and Failure of Polymer Microneedles.
Gittard Shaun D,Chen Bo,Xu Huadong,Ovsianikov Aleksandr,Chichkov Boris N,Monteiro-Riviere Nancy A,Narayan Roger J
Journal of adhesion science and technology
Microneedles are small-scale devices that may be used for drug delivery and biosensing. In this study, the forces required for mechanical failure, the modes of mechanical failure, as well as the mechanisms for microneedle penetration into porcine skin were examined. Microneedles produced from the acrylate-based polymer e-Shell 200 using an indirect rapid prototyping approach involving two-photon polymerization and poly(dimethylsiloxane) micromolding were found to possess sufficient strength for penetration of porcine skin. The failure forces were an order of magnitude greater than the forces necessary for full insertion into the skin. Bending was the most common form of failure; an increasing aspect ratio and a decreasing tip diameter were associated with lower failure forces. Video captured during skin penetration revealed that microneedle penetration into the skin occurred by means of a series of insertions and not by means of a single insertion event. Images obtained during and after skin penetration confirmed microneedle penetration of skin as well as transdermal delivery of lucifer yellow dye. These findings shed insight into the mechanisms of microneedle penetration and failure, facilitating design improvements for polymer microneedles.
Gene silencing following siRNA delivery to skin via coated steel microneedles: In vitro and in vivo proof-of-concept.
Chong Rosalind H E,Gonzalez-Gonzalez Emilio,Lara Maria F,Speaker Tycho J,Contag Christopher H,Kaspar Roger L,Coulman Sion A,Hargest Rachel,Birchall James C
Journal of controlled release : official journal of the Controlled Release Society
The development of siRNA-based gene silencing therapies has significant potential for effectively treating debilitating genetic, hyper-proliferative or malignant skin conditions caused by aberrant gene expression. To be efficacious and widely accepted by physicians and patients, therapeutic siRNAs must access the viable skin layers in a stable and functional form, preferably without painful administration. In this study we explore the use of minimally-invasive steel microneedle devices to effectively deliver siRNA into skin. A simple, yet precise microneedle coating method permitted reproducible loading of siRNA onto individual microneedles. Following recovery from the microneedle surface, lamin A/C siRNA retained full activity, as demonstrated by significant reduction in lamin A/C mRNA levels and reduced lamin A/C protein in HaCaT keratinocyte cells. However, lamin A/C siRNA pre-complexed with a commercial lipid-based transfection reagent (siRNA lipoplex) was less functional following microneedle coating. As Accell-modified "self-delivery" siRNA targeted against CD44 also retained functionality after microneedle coating, this form of siRNA was used in subsequent in vivo studies, where gene silencing was determined in a transgenic reporter mouse skin model. Self-delivery siRNA targeting the reporter (luciferase/GFP) gene was coated onto microneedles and delivered to mouse footpad. Quantification of reporter mRNA and intravital imaging of reporter expression in the outer skin layers confirmed functional in vivo gene silencing following microneedle delivery of siRNA. The use of coated metal microneedles represents a new, simple, minimally-invasive, patient-friendly and potentially self-administrable method for the delivery of therapeutic nucleic acids to the skin.
Development of in vivo impedance spectroscopy techniques for measurement of micropore formation following microneedle insertion.
Brogden Nicole K,Ghosh Priyanka,Hardi Lucia,Crofford Leslie J,Stinchcomb Audra L
Journal of pharmaceutical sciences
Microneedles (MNs) provide a minimally invasive means to enhance skin permeability by creating micron-scale channels (micropores) that provide a drug delivery pathway. Adequate formation of the micropores is critical to the success of this unique drug delivery technique. The objective of the current work was to develop sensitive and reproducible impedance spectroscopy techniques to monitor micropore formation in animal models and human subjects. Hairless guinea pigs, a Yucatan miniature pig, and human volunteers were treated with 100 MN insertions per site following an overnight prehydration period. Repeated measurements were made pre- and post-MN treatment using dry and gel Ag/AgCl electrodes applied with light verses direct pressure to hold the electrode to the skin surface. Impedance measurements dropped significantly post-MN application at all sites (p < 0.05, irrespective of electrode type or gel application), confirming micropore formation. In the Yucatan pig and human subjects, gel electrodes with direct pressure yielded the lowest variability (demonstrated by lower %relative standard deviation), whereas dry electrodes with direct pressure were superior in the guinea pigs. These studies confirm that impedance measurements are suitable for use in both clinical and animal research environments to monitor the formation of new micropores that will allow for drug delivery through the impermeable skin layers.
Vaccine delivery with microneedle skin patches in nonhuman primates.
DeMuth Peter C,Li Adrienne V,Abbink Peter,Liu Jinyan,Li Hualin,Stanley Kelly A,Smith Kaitlin M,Lavine Christy L,Seaman Michael S,Kramer Joshua A,Miller Andrew D,Abraham Wuhbet,Suh Heikyung,Elkhader Jamal,Hammond Paula T,Barouch Dan H,Irvine Darrell J
Effective transcutaneous immunization against hepatitis B virus by a combined approach of hydrogel patch formulation and microneedle arrays.
Guo Lei,Qiu Yuqin,Chen Jianmin,Zhang Suohui,Xu Bai,Gao Yunhua
Transcutaneous immunization (TCI) has many advantages compared with needle-based administrations. But the conventional TCI shows poor permeation of antigens across the skin barrier. In this study, Functional MicroArray (FMA) system was used to poke the skin and increase the permeability, and the hydrogel patch formulation was used as the carrier for transdermal delivery of hepatitis B surface antigen (HBsAg) and cholera toxin B (CTB) as an adjuvant. In vitro permeation of antigen was studied using porcine ear skin and rat abdominal skin. The results showed that FMA system could significantly increase the permeation of HBsAg across skin compared with conventional TCI. HBsAg loaded hydrogel formulation exhibited better antigenic thermostability than the liquid formulation. In vivo immunization studies were performed in mice, and the serum IgG titer, IgG2a/IgG1 ratio were measured. The results showed that TCI with FMA induced more potent immune responses than the groups without FMA pretreatment. CTB adjuvanted TCI group could induce higher IgG titers compared with the group without CTB. Furthermore, TCI group can maintain a longer duration of stable IgG titers compared with the intramuscular injection (IM) group. In conclusion, the FMA/hydrogel system was proved to be a potential vaccination strategy against hepatitis B virus.
Healing kinetics of microneedle-formed pores in PLGA films.
Mazzara J M,Balagna M A,Thouless M D,Schwendeman S P
Journal of controlled release : official journal of the Controlled Release Society
The spontaneous healing of aqueous pores in poly(D,L-lactic-co-glycolic acid) (PLGA) drug delivery systems has been identified to play a key role in terminating the burst release of large molecules, and to provide a means for novel aqueous-based microencapsulation. To examine healing of PLGA, pores were created of defined size and depth on the surface of thin PLGA films by stamping with blunt-tip microneedles. Pore dimensions on the micron-scale were relevant to surface pores of common PLGA microspheres and could be easily monitored by light microscopy. Most pores healed reproducibly at temperatures above the glass-transition temperature (T(g)) of the films, with healing times decreasing sharply with increasing temperature according to Williams-Landel-Ferry (WLF) behavior. It is suggested that healing is driven by high surface tension in the films and occurs through viscoelastic creep. Hydrated films healed at lower temperatures than dry films, consistent with a drop in Tg upon polymer hydration. Larger pores took longer to heal than smaller ones, while pores larger than 20 μm did not heal before significant polymer degradation occurred. Films of a less hydrophobic PLGA showed slower healing kinetics, attributed to a weaker surface tension driving force. Deeper pores showed signs of in-plane stress from spin-coating, and either ruptured or only partially healed when incubated wet and dry, respectively.
An experimental study of microneedle-assisted microparticle delivery.
Zhang Dongwei,Das Diganta B,Rielly Chris D
Journal of pharmaceutical sciences
A set of well-defined experiments has been carried out to explore whether microneedles (MNs) can enhance the penetration depths of microparticles moving at high velocity such as those expected in gene guns for delivery of gene-loaded microparticles into target tissues. These experiments are based on applying solid MNs that are used to reduce the effect of mechanical barrier function of the target so as to allow delivery of microparticles at less imposed pressure as compared with most typical gene guns. Further, a low-cost material, namely, biomedical-grade stainless steel microparticle with size ranging between 1 and 20 μm, has been used in this study. The microparticles are compressed and bound in the form of a cylindrical pellet and mounted on a ground slide, which are then accelerated together by compressed air through a barrel. When the ground slide reaches the end of the barrel, the pellet is separated from the ground slide and is broken down into particle form by a mesh that is placed at the end of the barrel. Subsequently, these particles penetrate into the target. This paper investigates the implications of velocity of the pellet along with various other important factors that affect the particle delivery into the target. Our results suggest that the particle passage increases with an increase in pressure, mesh pore size, and decreases with increase in polyvinylpyrrolidone concentration. Most importantly, it is shown that MNs increase the penetration depths of the particles.
Performance and characteristics evaluation of a sodium hyaluronate-based microneedle patch for a transcutaneous drug delivery system.
Hiraishi Yasuhiro,Nakagawa Takeshi,Quan Ying-Shu,Kamiyama Fumio,Hirobe Sachiko,Okada Naoki,Nakagawa Shinsaku
International journal of pharmaceutics
The MicroHyala(®) microneedle (MN) patch was developed to provide a simple, safe, and effective drug delivery system. In this study, we examined the performance and characteristics of our fabricated MN patch to identify potential quality issues with future commercial application. Mechanical failure force analysis identified that the strength of the MN patch was affected by environmental humidity, because higher moisture levels weakened the strength of the MN. Incorporation of all-trans retinoic acid (ATRA) or ovalbumin (OVA) into the MN patch decreased the mechanical failure force by almost 50% of the strength of placebo (without drug) patches. ATRA-loaded MN patches displayed good stability after storage at 4 °C, with more than 90% and 85% of the drug remaining in the patch after 8 and 24 weeks of storage, respectively. Tetanus toxoid- and diphtheria toxoid-loaded MN patches stored for 12 months induced robust antigen-specific immune responses similar to the responses by freshly prepared MN patches. Fluorescence imaging findings suggested that prolonged antigen deposition was induced by MN-mediated fluorescein isothiocyanate-labeled (FITC)-OVA vaccination. Overall, although the strength of MN requires improvement, our developed MN patch appears to be an effective pharmaceutical product providing a simple, safe, and relatively painless approach.
Efficacy of fractional microneedle radiofrequency device in the treatment of primary axillary hyperhidrosis: a pilot study.
Kim Miri,Shin Jae Yong,Lee Jungsoo,Kim Ji Young,Oh Sang Ho
Dermatology (Basel, Switzerland)
BACKGROUND:Fractional microneedle radiofrequency (FMR) devices deliver energy to the deep dermis through insulated microneedles without destroying the epidermis. These FMR devices have been shown to be effective for the treatment of wrinkles, acne scars and large pores. In this study it was postulated that FMR energy could specifically affect the sweat glands, preserving the skin surface even if sweat glands were seated in the deep dermis. OBJECTIVE:To evaluate the efficacy and safety of FMR for primary axillary hyperhidrosis (PAH) treatment and to conduct a histological analysis before and after treatment. METHODS:Twenty patients with PAH had 2 sessions of bipolar FMR treatment at 4-week intervals. Clinical improvement was evaluated using a Hyperhidrosis Disease Severity Scale (HDSS) and photographs were taken using the starch-iodine test at every visit and 2 months after the last treatment. The amount of sweat reduction was indirectly assessed using a Tewameter™. Skin biopsies were obtained from 3 of the enrolled patients before and after treatment. The satisfaction and adverse reactions of the research participants were recorded at every follow-up visit. RESULTS:HDSS scores decreased significantly from a baseline of 3.3 to 1.5 and 1.8 after the first and second months of posttreatment follow-up sessions, respectively (p < 0.001). In response to a subjective assessment at 1 month after the second treatment, 75% of patients (n = 15) had an HDSS score of 1 or 2, and 70% of patients (n = 14) expressed more than 50% improvement in their sweating. The starch-iodine reaction was also remarkably reduced in 95% of patients (n = 19) after FMR treatment. Histological findings showed a decrease in the number and size of both apocrine and eccrine glands 1 month after the final treatment. Side effects were minimal and included mild discomfort, transient swelling and postinflammatory hyperpigmentation. CONCLUSION:FMR treatment was effective for the treatment of PAH without significant adverse reactions due to direct volumetric heating of the lower dermis.
Fractionated microneedle radiofrequency for the treatment of periorbital wrinkles.
Kim Jae Kyung,Roh Mi Ryung,Park Gyeong-hun,Kim Youn Jin,Jeon In Kyung,Chang Sung Eun
The Journal of dermatology
Non-ablative bipolar and monopolar radiofrequency devices have been shown to be effective for the treatment of facial wrinkles. Recently, novel fractionated microneedle radiofrequency (FMRF) devices have been introduced. The aim of this study was to evaluate the clinical effectiveness and safety of FMRF for the treatment of periorbital wrinkles. Eleven women, aged 34-59 years, with periorbital wrinkles underwent three sessions of FMRF at 3-week intervals with a follow-up period of 3 months after treatment. Clinical improvement was evaluated using the Fitzpatrick Wrinkle Classification System (FWCS) and subjective satisfaction on a visual analog scale (VAS). The FWCS scores demonstrated significant improvement in periorbital wrinkles after treatment (P < 0.001). A satisfaction VAS score of more than 5, indicating high satisfaction, was obtained from 10 of 11 patients (91%) 3 months after treatment, and the mean satisfaction VAS score (n = 11) was 6.7. Patients undergoing treatment reported minimal pain, and neither long-lasting side-effects nor significant downtime was noted. This clinical study suggests that FMRF is a safe and tolerable method for successful treatment of periorbital wrinkles.
Comparison of microneedle fractional radiofrequency therapy with intradermal botulinum toxin a injection for periorbital rejuvenation.
Jeon In Kyung,Chang Sung Eun,Park Gyeong-Hun,Roh Mi Ryung
Dermatology (Basel, Switzerland)
BACKGROUND:For periorbital rejuvenation, injection of botulinum toxin A (BoNT/A) is known to improve both static as well as dynamic wrinkles. A microneedle fractional radiofrequency (MFR) device was recently developed and is a novel and promising tool. OBJECTIVE:This study compares the effects of these two treatment modalities on periorbital static wrinkles and lines. METHODS:Twelve healthy women aged 20-59 years with periorbital wrinkles participated in this study. Each patient received one session of intradermal injection of BoNT/A on the left periorbital area and three sessions of MFR on the right. Clinical improvement, skin elasticity and subjective satisfaction were evaluated at every visit (baseline, 3, 6 and 18 weeks). RESULTS:BoNT/A injection showed superior effects at 3 and 6 weeks. However, the MFR device showed better improvement at 18 weeks. In skin biopsies, the expression of procollagen 3 and elastin was increased on the MFR side compared to the untreated skin and the BoNT/A injection side. The patient satisfaction surveys at 3 weeks showed better satisfaction on the BoNT/A treatment side compared to the MFR treatment side. At 18 weeks, there were no significant differences in patient satisfaction between the two sides. CONCLUSION:BoNT/A injection rapidly improved periorbital wrinkles, but the effect decreased up to week 18. Compared to BoNT/A injection, MFR therapy showed gradual and long-term improvement in periorbital rejuvenation.
Langerin negative dendritic cells promote potent CD8+ T-cell priming by skin delivery of live adenovirus vaccine microneedle arrays.
Bachy Veronique,Hervouet Catherine,Becker Pablo D,Chorro Laurent,Carlin Leo M,Herath Shanthi,Papagatsias Timos,Barbaroux Jean-Baptiste,Oh Sea-Jin,Benlahrech Adel,Athanasopoulos Takis,Dickson George,Patterson Steven,Kwon Sung-Yun,Geissmann Frederic,Klavinskis Linda S
Proceedings of the National Academy of Sciences of the United States of America
Stabilization of virus protein structure and nucleic acid integrity is challenging yet essential to preserve the transcriptional competence of live recombinant viral vaccine vectors in the absence of a cold chain. When coupled with needle-free skin delivery, such a platform would address an unmet need in global vaccine coverage against HIV and other global pathogens. Herein, we show that a simple dissolvable microneedle array (MA) delivery system preserves the immunogenicity of vaccines encoded by live recombinant human adenovirus type 5 (rAdHu5). Specifically, dried rAdHu5 MA immunization induced CD8(+) T-cell expansion and multifunctional cytokine responses equipotent with conventional injectable routes of immunization. Intravital imaging demonstrated MA cargo distributed both in the epidermis and dermis, with acquisition by CD11c(+) dendritic cells (DCs) in the dermis. The MA immunizing properties were attributable to CD11c(+) MHCII(hi) CD8α(neg) epithelial cell adhesion molecule (EpCAM(neg)) CD11b(+) langerin (Lang; CD207)(neg) DCs, but neither Langerhans cells nor Lang(+) DCs were required for CD8(+) T-cell priming. This study demonstrates an important technical advance for viral vaccine vectors progressing to the clinic and provides insights into the mechanism of CD8(+) T-cell priming by live rAdHu5 MAs.
Skin dendritic cell targeting via microneedle arrays laden with antigen-encapsulated poly-D,L-lactide-co-glycolide nanoparticles induces efficient antitumor and antiviral immune responses.
Zaric Marija,Lyubomska Oksana,Touzelet Olivier,Poux Candice,Al-Zahrani Sharifah,Fay Francois,Wallace Leah,Terhorst Dorothea,Malissen Bernard,Henri Sandrine,Power Ultan F,Scott Christopher J,Donnelly Ryan F,Kissenpfennig Adrien
The efficacious delivery of antigens to antigen-presenting cells (APCs), in particular, to dendritic cells (DCs), and their subsequent activation remains a significant challenge in the development of effective vaccines. This study highlights the potential of dissolving microneedle (MN) arrays laden with nanoencapsulated antigen to increase vaccine immunogenicity by targeting antigen specifically to contiguous DC networks within the skin. Following in situ uptake, skin-resident DCs were able to deliver antigen-encapsulated poly-d,l-lactide-co-glycolide (PGLA) nanoparticles to cutaneous draining lymph nodes where they subsequently induced significant expansion of antigen-specific T cells. Moreover, we show that antigen-encapsulated nanoparticle vaccination via microneedles generated robust antigen-specific cellular immune responses in mice. This approach provided complete protection in vivo against both the development of antigen-expressing B16 melanoma tumors and a murine model of para-influenza, through the activation of antigen-specific cytotoxic CD8(+) T cells that resulted in efficient clearance of tumors and virus, respectively. In addition, we show promising findings that nanoencapsulation facilitates antigen retention into skin layers and provides antigen stability in microneedles. Therefore, the use of biodegradable polymeric nanoparticles for selective targeting of antigen to skin DC subsets through dissolvable MNs provides a promising technology for improved vaccination efficacy, compliance, and coverage.
Intracranial hyperthermia through local photothermal heating with a fiberoptic microneedle device.
Hood R Lyle,Rossmeisl John H,Andriani Rudy T,Wilkinson Ashley R,Robertson John L,Rylander Christopher G
Lasers in surgery and medicine
BACKGROUND AND OBJECTIVES:The fiberoptic microneedle device (FMD) seeks to leverage advantages of both laser-induced thermal therapy (LITT) and convection-enhanced delivery (CED) to increase volumetric dispersal of locally infused chemotherapeutics through sub-lethal photothermal heat generation. This study focused on determination of photothermal damage thresholds with 1,064 nm light delivered through the FMD into in vivo rat models. MATERIALS AND METHODS:FMDs capable of co-delivering laser energy and fluid agents were fabricated through a novel off-center splicing technique involving fusion of a multimode fiberoptic to light-guiding capillary tubing. FMDs were positioned at a depth of 2.5 mm within the cerebrum of male rats with fluoroptic temperature probes placed within 1 mm of the FMD tip. Irradiation (without fluid infusion) was conducted at laser powers of 0 (sham), 100, 200, 500, or 750 mW. Evans blue-serum albumin conjugated complex solution (EBA) and laser energy co-delivery were performed in a second set of preliminary experiments. RESULTS:Maximum, steady-state temperatures of 38.7 ± 1.6 and 42.0 ± 0.9 °C were measured for the 100 and 200 mW experimental groups, respectively. Histological investigation demonstrated needle insertion damage alone for sham and 100 mW irradiations. Photothermal damage was detected at 200 mW, although observable thermal damage was limited to a small penumbra of cerebral cortical microcavitation and necrosis that immediately surrounded the region of FMD insertion. Co-delivery of EBA and laser energy presented increased volumetric dispersal relative to infusion-only controls. CONCLUSION:Fluoroptic temperature sensing and histopathological assessments demonstrated that a laser power of 100 mW results in sub-lethal brain hyperthermia, and the optimum, sub-lethal target energy range is likely 100-200 mW. The preliminary FMD-CED experiments confirmed the feasibility of augmenting fluid dispersal using slight photothermal heat generation, demonstrating the FMD's potential as a way to increase the efficacy of CED in treating MG.
Influence of array interspacing on the force required for successful microneedle skin penetration: theoretical and practical approaches.
Olatunji Ololade,Das Diganta B,Garland Martin J,Belaid Luc,Donnelly Ryan F
Journal of pharmaceutical sciences
Insertion behaviour of microneedle (MN) arrays depends upon the mechanical properties of the skin and, MN geometry and distribution in an array. In addressing this issue, this paper studies MN array insertion mechanism into skin and provides a simple quantitative basis to relate the insertion force with distance between two MNs. The presented framework is based on drawing an analogy between a beam on an elastic foundation and mechanism of needle insertion, where insertion force is separated into different components. A theoretical analysis indicates that insertion force decreases as interspacing increases. For a specified skin type, insertion force decreased from 0.029 to 0.028 N/MN when interspacing at MN tip was increased from 50 μm (350 μm at MN base) to 150 μm (450 μm at MN base). However, dependence of insertion force seems to decrease as the interspacing is increased beyond 150 μm. To assess the validity of the proposed model, a series of experiments was carried out to determine the force required for skin insertion of MN. Experiments performed at insertion speed of 0.5 and 1.0 mm/s yielded insertion force values of 0.030 and 0.0216 N, respectively, for 30 μm interspacing at MN base (330 μm interspacing at tip) and 0.028 and 0.0214 N, respectively, for 600 μm interspacing at MN base (900 μm interspacing at tip). Results from theoretical analysis and finite element modelling agree well with experimental results, which show MN interspacing only begins to affect insertion force at low interspacing (<150 μm interspacing at MN base). This model provides a framework for optimising MN devices, and should aid development of suitable application method and determination of force for reliable insertion into skin.
Enhanced transcutaneous immunization via dissolving microneedle array loaded with liposome encapsulated antigen and adjuvant.
Guo Lei,Chen Jianmin,Qiu Yuqin,Zhang Suohui,Xu Bai,Gao Yunhua
International journal of pharmaceutics
Transcutaneous immunization (TCI) with dissolving microneedle arrays (DMAs) is a promising vaccine administration method. In this work, we developed a TCI device consisting of dissolving polyvinylpyrrolidone (PVP) microneedles array, where in the tips are loaded with antigen and adjuvant encapsulated in liposomes. The microneedles could effectively be inserted into the skin and completely dissolve within 3 min. As a test-case, we selected ovalbumin (OVA) as a model antigen, CpG OND as adjuvant and cationic liposome (Lip) as a microparticulate vehicle for co-deliver antigens and adjuvant. Mice were immunized transcutaneously with DMAs containing OVA, OVA-CpG OND, OVA encapsulated in Lip, OVA-CpG OND encapsulated in Lip and conventional intramuscular injection (IM) with OVA solution, respectively. The results show that the anti-OVA IgG antibody level in the group immunized with the DMA containing OVA-CpG OND encapsulated in Lip was significantly higher than that of the other groups. Furthermore, it significantly increased the level of IgG2a (P<0.05) and achieved the shift of immune type from predominate Th2 type to a balance Th1/Th2 type. In conclusion, the DMA TCI device can effectively deliver the Lip encapsulating CpG OND-OVA into skin, enhancing the immune response and change the immune type.
Spatially controlled photothermal heating of bladder tissue through single-walled carbon nanohorns delivered with a fiberoptic microneedle device.
Hood R Lyle,Carswell William F,Rodgers Amanda,Kosoglu Mehmet A,Rylander Marissa Nichole,Grant David,Robertson John L,Rylander Christopher G
Lasers in medical science
Laser-based photothermal therapies for urothelial cell carcinoma (UCC) are limited to thermal ablation of superficial tumors, as treatment of invasive lesions is hampered by shallow light penetration in bladder tissue at commonly used therapeutic wavelengths. This study evaluates the utilization of sharp, silica, fiberoptic microneedle devices (FMDs) to deliver single-walled carbon nanohorns (SWNHs) serving as exogenous chromophores in conjunction with a 1,064-nm laser to amplify thermal treatment doses in a spatially controlled manner. Experiments were conducted to determine the lateral and depth dispersal of SWNHs in aqueous solution (0.05 mg/mL) infused through FMDs into the wall of healthy, inflated, ex vivo porcine bladders. SWNH-perfused bladder regions were irradiated with a free-space, CW, 1,064-nm laser in order to determine the SWNH efficacy as exogenous chromophores within the organ. SWNHs infused at a rate of 50 μL/min resulted in an average lateral expansion rate of 0.36 ± 0.08 cm(2)/min. Infused SWNHs dispersal depth was limited to the urothelium and muscular propria for 50 μL/min infusions of 10 min or less, but dispersed through the entire thickness after a 15-min infusion period. Irradiation of SWNH-perfused bladder tissue with 1,064 nm laser light at 0.95 W/cm(2) over 40 s exhibited a maximum increase of approximately 19 °C compared with an increase of approximately 3 °C in a non-perfused control. The results indicate that these silica FMDs can successfully penetrate into the bladder wall to rapidly distribute SWNHs with some degree of lateral and depth control and that SWNHs may be a viable exogenous chromophore for photothermal amplification of laser-based UCC treatments.
Development of a codrug approach for sustained drug delivery across microneedle-treated skin.
Ghosh Priyanka,Pinninti Raghotham R,Hammell Dana C,Paudel Kalpana S,Stinchcomb Audra L
Journal of pharmaceutical sciences
Microneedle (MN) enhanced transdermal drug delivery enables the transport of a host of molecules that cannot be delivered across the skin by passive diffusion alone. However, the skin being a self-regenerating organ heals itself and thus prevents delivery of molecules through micropores for a 7-day time period, the ideal transdermal delivery goal. Hence, it is necessary to employ a second drug molecule, a cyclooxygenase inhibitor to enhance pore lifetime by decreasing local subclinical inflammatory response following MN treatment. A codrug approach using a 3-O-ester codrug of the model drug naltrexone (NTX) with diclofenac (DIC), a cyclooxygenase inhibitor, was tested in vitro as well as in vivo to look at stability, bioconversion and permeation. The results indicated that the approach could be useful for transdermal drug delivery of NTX from a single patch for a week, but stability and solubility optimization will be required for the codrug before it can deliver significant levels of NTX into the plasma. The skin concentration of DIC was high enough to keep the pores open in vivo in a hairless guinea pig model as demonstrated by day seven pore visualization studies.
Influenza subunit vaccine coated microneedle patches elicit comparable immune responses to intramuscular injection in guinea pigs.
Kommareddy S,Baudner B C,Bonificio A,Gallorini S,Palladino G,Determan A S,Dohmeier D M,Kroells K D,Sternjohn J R,Singh M,Dormitzer P R,Hansen K J,O'Hagan D T
Delivery of influenza vaccine using innovative approaches such as microneedles has been researched extensively in the past decade. In this study we present concentration followed by formulation and coating of monobulks from 2008/2009 seasonal vaccine on to 3M's solid microstructured transdermal system (sMTS) by a GMP-scalable process. The hemagglutinin (HA) in monobulks was concentrated by tangential flow filtration (TFF) to achieve HA concentrations as high as 20mg/ml. The stability of the coated antigens was evaluated by the functional assay, single radial immunodiffusion (SRID). The data generated show stability of the coated antigen upon storage at 4°C and room temperature in the presence of desiccant for at least 8 weeks. Freeze-thaw stability data indicate the stability of the coated antigen in stressed conditions. The vaccine coated microstructures were evaluated in vivo in a guinea pig model, and resulted in immune titers comparable to the traditional trivalent vaccine administered intramuscularly. The data presented indicate the potential use of the technology in delivery of influenza vaccine. This paper also addresses the key issues of stability of coated antigen, reproducibility and scalability of the processes used in preparation of influenza vaccine coated microneedle patches that are important in developing a successful product.
Fiberoptic microneedle device facilitates volumetric infusate dispersion during convection-enhanced delivery in the brain.
Hood R Lyle,Andriani Rudy T,Emch Samantha,Robertson John L,Rylander Christopher G,Rossmeisl John H
Lasers in surgery and medicine
BACKGROUND AND OBJECTIVES:A fiberoptic microneedle device (FMD) was designed and fabricated for the purpose of enhancing the volumetric dispersal of macromolecules delivered to the brain through convection-enhanced delivery (CED) by concurrent delivery of sub-lethal photothermal hyperthermia. This study's objective was to demonstrate enhanced dispersal of fluid tracer molecules through co-delivery of 1,064 nm laser energy in an in vivo rodent model. MATERIALS AND METHODS:FMDs capable of co-delivering fluids and laser energy through a single light-guiding capillary tube were fabricated. FMDs were stereotactically inserted symmetrically into both cerebral hemispheres of 16 anesthetized rats to a depth of 1.5 mm. Laser irradiation (1,064 nm) at 0 (control), 100, and 200 mW was administered concurrently with CED infusions of liposomal rhodamine (LR) or gadolinium-Evans blue-serum albumin conjugated complex (Gd-EBA) at a flow rate of 0.1 µl/min for 1 hour. Line pressures were monitored during the infusions. Rodents were sacrificed immediately following infusion and their brains were harvested, frozen, and serially cryosectioned for histopathologic and volumetric analyses. RESULTS:Analysis by ANOVA methods demonstrated that co-delivery enhanced volumetric dispersal significantly, with measured volumes of 15.8 ± 0.6 mm(3) for 100 mW compared to 10.0 ± 0.4 mm(3) for its fluid only control and 18.0 ± 0.3 mm(3) for 200 mW compared to 10.3 ± 0.7 mm(3) for its fluid only control. Brains treated with 200 mW co-delivery exhibited thermal lesions, while 100 mW co-deliveries were associated with preservation of brain cytoarchitecture. CONCLUSION:Both lethal and sub-lethal photothermal hyperthermia substantially increase the rate of volumetric dispersal in a 1 hour CED infusion. This suggests that the FMD co-delivery method could reduce infusion times and the number of catheter insertions into the brain during CED procedures.
Rapidly-dissolvable microneedle patches via a highly scalable and reproducible soft lithography approach.
Moga Katherine A,Bickford Lissett R,Geil Robert D,Dunn Stuart S,Pandya Ashish A,Wang Yapei,Fain John H,Archuleta Christine F,O'Neill Adrian T,Desimone Joseph M
Advanced materials (Deerfield Beach, Fla.)
Microneedle devices for transdermal drug delivery have recently become an attractive method to overcome the diffusion-limiting epidermis and effectively transport therapeutics to the body. Here, we demonstrate the fabrication of highly reproducible and completely dissolvable polymer microneedles on flexible water-soluble substrates. These biocompatible microneedles (made by using a soft lithography process known as PRINT) showed efficacy in piercing both murine and human skin samples and delivering a fluorescent drug surrogate to the tissue.
Effect of lipophilicity on microneedle-mediated iontophoretic transdermal delivery across human skin in vitro.
Pawar Kasturi R,Smith Forrest,Kolli Chandra Sekhar,Babu R Jayachandra
Journal of pharmaceutical sciences
The effect of lipophilicity of drug on the microneedle (MN)-mediated iontophoretic delivery across dermatomed human skin was studied. Beta blockers with similar pKa but varied log P values were selected as model drugs in this study. Iontophoresis (ITP) or MNs, when used independently, increased the transdermal flux of beta blockers as compared with passive delivery (PD). ITP across the MN-treated skin (MN + ITP) increased the permeation rate of all beta blockers as compared with PD (p < 0.001). The enhancement ratios (ER) for hydrophilic molecules (atenolol and sotalol) were 71- and 78-fold higher for ITP + MN as compared with PD. However, for lipophilic molecule such as propranolol, there was 10-fold increase in the ER as compared with PD. These observations were further substantiated by the skin retention data; an inverse relationship between the skin retention and the hydrophilicity of the drug was observed. The results in the present study point out that the lipophilicity of the molecule plays a significant role on the electrically assisted transdermal delivery of drugs across the microporated skin. Using the combination of ITP + MN, hydrophilic drugs (atenolol and sotalol) were delivered at a much higher rate as compared with lipophilic molecules (propranolol and acebutolol).
Microneedle integrated transdermal patch for fast onset and sustained delivery of lidocaine.
Kochhar Jaspreet Singh,Lim Wan Xuan Selina,Zou Shui,Foo Wei Yan,Pan Jing,Kang Lifeng
Lidocaine as an analgesic is of particular interest in both acute and chronic pain conditions and is used via injections or transdermal patches. While injections are associated with problems such as patient incompliance, topical administration of lidocaine using patches is less efficient due to variability of drug absorption among individuals, slower drug permeation through the skin, and hence a resultant undesirable delay in analgesic effects. To address this clinical problem, we developed a microneedle integrated transdermal patch (MITP), using a photolithography based process, in which microneedles create micrometer-sized channels in the skin to deliver lidocaine rapidly, while the reservoir patch holding the bulk of the drug enables higher drug loading and carries on to release the drug for prolonged periods. We demonstrated a new approach of drug delivery using microneedles, where drugs diffuse out of microneedles through the porous channels left by dissolving drug particles. MITP was shown to be able to encapsulate up to 70 mg of lidocaine. In vitro permeation through rat skin demonstrated that MITP delivered a significantly higher amount of lidocaine than a commercial patch and with a faster onset of drug permeation.
Dissolving polymer microneedle patches for rapid and efficient transdermal delivery of insulin to diabetic rats.
Ling Ming-Hung,Chen Mei-Chin
This study presents a dissolving microneedle patch, composed of starch and gelatin, for the rapid and efficient transdermal delivery of insulin. The microneedles completely dissolve after insertion into the skin for 5 min, quickly releasing their encapsulated payload into the skin. A histological examination shows that the microneedles have sufficient mechanical strength to be inserted in vitro into porcine skin to a depth of approximately 200 μm and in vivo into rat skin to 200-250 μm depth. This penetration depth does not induce notable skin irritation or pain sensation. To evaluate the feasibility of using these dissolving microneedles for diabetes treatment insulin-loaded microneedles were administered to diabetic rats using a homemade applicator. Pharmacodynamic and pharmacokinetic results show a similar hypoglycemic effect in rats receiving insulin-loaded microneedles and a subcutaneous injection of insulin. The relative pharmacological availability and relative bioavailability of insulin were both approximately 92%, demonstrating that insulin retains its pharmacological activity after encapsulation and release from the microneedles. Storage stability analysis confirms that more than 90% of the insulin remained in the microneedles even after storage at 25 or 37°C for 1 month. These results confirm that the proposed starch/gelatin microneedles enable stable encapsulation of bioactive molecules and have great potential for transdermal delivery of protein drugs in a relatively painless, rapid, and convenient manner.
A bio-inspired swellable microneedle adhesive for mechanical interlocking with tissue.
Yang Seung Yun,O'Cearbhaill Eoin D,Sisk Geoffroy C,Park Kyeng Min,Cho Woo Kyung,Villiger Martin,Bouma Brett E,Pomahac Bohdan,Karp Jeffrey M
Achieving significant adhesion to soft tissues while minimizing tissue damage poses a considerable clinical challenge. Chemical-based adhesives require tissue-specific reactive chemistry, typically inducing a significant inflammatory response. Staples are fraught with limitations including high-localized tissue stress and increased risk of infection, and nerve and blood vessel damage. Here inspired by the endoparasite Pomphorhynchus laevis, which swells its proboscis to attach to its host's intestinal wall, we have developed a biphasic microneedle array that mechanically interlocks with tissue through swellable microneedle tips, achieving ~3.5-fold increase in adhesion strength compared with staples in skin graft fixation, and removal force of ~4.5 N cm(-2) from intestinal mucosal tissue. Comprising a poly(styrene)-block-poly(acrylic acid) swellable tip and non-swellable polystyrene core, conical microneedles penetrate tissue with minimal insertion force and depth, yet high adhesion strength in their swollen state. Uniquely, this design provides universal soft tissue adhesion with minimal damage, less traumatic removal, reduced risk of infection and delivery of bioactive therapeutics.
Hippocampal neurogenesis and the brain repair response to brief stereotaxic insertion of a microneedle.
Song Shijie,Song Shuojing,Cao Chuanhai,Lin Xiaoyang,Li Kunyu,Sava Vasyl,Sanchez-Ramos Juan
Stem cells international
We tested the hypothesis that transient microinjury to the brain elicits cellular and humoral responses that stimulate hippocampal neurogenesis. Brief stereotaxic insertion and removal of a microneedle into the right hippocampus resulted in (a) significantly increased expression of granulocyte-colony stimulating factor (G-CSF), the chemokine MIP-1a, and the proinflammatory cytokine IL12p40; (b) pronounced activation of microglia and astrocytes; and (c) increase in hippocampal neurogenesis. This study describes immediate and early humoral and cellular mechanisms of the brain's response to microinjury that will be useful for the investigation of potential neuroprotective and deleterious effects of deep brain stimulation in various neuropsychiatric disorders.
Microneedle Biosensor: A Method for Direct Label-free Real Time Protein Detection.
Esfandyarpour Rahim,Esfandyarpour Hesaam,Javanmard Mehdi,Harris James S,Davis Ronald W
Sensors and actuators. B, Chemical
Here we present the development of an array of electrical micro-biosensors in a microfluidic channel, called microneedle biosensors. A microneedle biosensor is a real-time, label-free, direct electrical detection platform, which is capable of high sensitivity detection, measuring the change in ionic current and impedance modulation, due to the presence or reaction of biomolecules such as proteins and nucleic acids. In this study, we successfully fabricated and electrically characterized the sensors and demonstrated successful detection of target protein. In this study, we used biotinylated bovine serum albumin as the receptor and streptavidin as the target analyte.
Endovascular cannulation with a microneedle for central retinal vein occlusion.
Kadonosono Kazuaki,Yamane Shin,Arakawa Akira,Inoue Maiko,Yamakawa Tadashi,Uchio Eiichi,Yanagi Yasuo,Amano Shiro
We developed a new surgical treatment in which a microneedle is used for retinal endovascular cannulation to treat eyes with central retinal vein occlusion by flushing thrombus out of the central retinal vein as it passes through the lamina cribrosa. The eyes of 12 consecutive patients (12 eyes) with central retinal vein occlusion were successfully treated using this novel treatment. At 24 weeks after surgery, 9 of 12 eyes had gained more than 15 letters in best-corrected visual acuity, and the mean decrease in central foveal thickness was 271.1 μm. Few complications were observed. The microneedle is stiff and sharp enough to facilitate retinal endovascular cannulation in eyes with central retinal vein occlusion. This new technique is a promising treatment of macular edema due to central retinal vein occlusion.
Microarrays and microneedle arrays for delivery of peptides, proteins, vaccines and other applications.
Chandrasekhar Saradha,Iyer Lavanya K,Panchal Jainik P,Topp Elizabeth M,Cannon John B,Ranade Vasant V
Expert opinion on drug delivery
INTRODUCTION:Peptide and protein microarray and microneedle array technology provides direct information on protein function and potential drug targets in drug discovery and delivery. Because of this unique ability, these arrays are well suited for protein profiling, drug target identification/validation and studies of protein interaction, biochemical activity, immune responses, clinical prognosis and diagnosis and for gene, protein and drug delivery. AREAS COVERED:The aim of this review is to describe and summarize past and recent developments of microarrays in their construction, characterization and production and applications of microneedles in drug delivery. The scope and limitations of various technologies in this respect are discussed. EXPERT OPINION:This article offers a review of microarray/microneedle technologies and possible future directions in targeting and in the delivery of pharmacologically active compounds for unmet needs in biopharmaceutical research. A better understanding of the production and use of microarrays and microneedles for delivery of peptides, proteins and vaccines is needed.
Development and clinical study of a self-dissolving microneedle patch for transcutaneous immunization device.
Hirobe Sachiko,Azukizawa Hiroaki,Matsuo Kazuhiko,Zhai You,Quan Ying-Shu,Kamiyama Fumio,Suzuki Hiroshi,Katayama Ichiro,Okada Naoki,Nakagawa Shinsaku
PURPOSE:We previously reported the safety and efficacy in animal experiments of transcutaneous immunization (TCI) using a self-dissolving microneedle patch (MicroHyala; MH) made of hyaluronic acid and collagen. However, this MH was an unsuitable TCI device for the human skin, as collagen is suspected to induce inflammation. In this study, we developed an improved collagen-free MH (new-MH) and conducted clinical study to evaluate the fundamental properties and safety in human. METHODS:Microneedle dissolution, skin irritation, and antigen-specific antibody production about new-MH were measured in mice and/or rats. On the basis of the results, the clinical study was conducted in healthy volunteers to evaluate local and systemic adverse events caused by new-MH application. RESULTS:We confirmed that the microneedles of new-MH, as well as those on our old-MH that contained collagen, could easily pierce stratum corneum without severe skin irritation, and that TCI using new-MH efficiently increased antibody titer with comparable to TCI using old-MH. Application of new-MH caused no severe adverse reactions in 20 healthy volunteers enrolled in a clinical study. CONCLUSIONS:These results verified that new-MH is a safe TCI device in human, and greatly encouraged us to advance PI/PII clinical studies of antigen-loaded new-MH.
Microneedle-assisted percutaneous delivery of naltrexone hydrochloride in yucatan minipig: in vitro-in vivo correlation.
Milewski Mikolaj,Paudel Kalpana S,Brogden Nicole K,Ghosh Priyanka,Banks Stan L,Hammell Dana C,Stinchcomb Audra L
Although microneedle-assisted transdermal drug delivery has been the subject of multiple scientific investigations, very few attempts have been made to quantitatively relate in vitro and in vivo permeation. The case of naltrexone hydrochloride is not an exception. In the present study, a pharmacokinetic profile obtained following a "poke and patch" microneedle application method in the Yucatan minipig is reported. The profile demonstrates a rapid achievement of maximum naltrexone hydrochloride plasma concentration followed by a relatively abrupt concentration decline. No steady state was achieved in vivo. In an attempt to correlate the present in vivo findings with formerly published in vitro steady-state permeation data, a diffusion-compartmental mathematical model was developed. The model incorporates two parallel permeation pathways, barrier-thickness-dependent diffusional resistance, microchannel closure kinetics, and a pharmacokinetic module. The regression analysis of the pharmacokinetic data demonstrated good agreement with an independently calculated microchannel closure rate and in vitro permeation data. Interestingly, full-thickness rather than split-thickness skin employed in in vitro diffusion experiments provided the best correlation with the in vivo data. Data analysis carried out with the model presented herein provides new mechanistic insight and permits predictions with respect to pharmacokinetics coupled with altered microchannel closure rates.
In vivo histological evaluation of non-insulated microneedle radiofrequency applicator with novel fractionated pulse mode.
Harth Yoram,Frank Ido
Journal of drugs in dermatology : JDD
INTRODUCTION:Microneedle radiofrequency is a novel method that allows non-thermal penetration of the epidermis followed by RF coagulation in selected depth of the dermis surrounded by zone of non-coagulative volumetric heating. The first generation of Microneedle RF applicators used insulated needles. These treatments were limited by a few factors, including low volume of dermal heating, lack of effect in the papillary dermis and pinpoint bleeding during the treatment. The system tested in this study (EndyMed PRO, Intensif applicator, EndyMed Medical, Cesarea, Israel) utilizes special extra sharp tapered non-insulated microneedles and a special pulse mode, allowing full coagulation during treatment and higher effective volume of dermal heat. METHODS:After Ethics Committee approval, one female pig (Type Large white X Landrace, 34 Kg) was chosen for the study. The animal was anesthetized using Ketamine, Xylazin and Isofluran. The EndyMed PRO, Intensif applicator (was used for treatment with different needle depth penetration (1 mm-3.5 mm) and in multiple energy settings. Six mm punch biopsies were harvested for histological analysis at the following time points: immediately after the treatment, 4 days after the treatment and 14 days after the treatment. H&E and Masson-Trichrome stains were processed. RESULTS:Visual inspection of the treated skin, immediately after the treatment, revealed arrays of pinpoint erythematous papules surrounded by undamaged epidermal tissue. Treatment field showed no sign of bleeding. Mild to moderate Erythema and Edema developed a few minutes after the treatment, varying according to the total energy delivered. The histologies taken 4-day after therapy showed in all energy settings, dry micro crusts over the treatment zones, with full healing of epidermis. In the 14-day specimens there was a replacement of the crusts/debris by a normal looking stratum corneum with complete healing of epidermis and dermis. DISCUSSION:The current in vivo study confirms that the EndyMed PRO Intensif applicator effective and predictable tool to create cylindrical micro zones of coagulation in the papillary and reticular dermis with minimal damage to the epidermis. The histologies taken 4 days and 14 days after treatment show rapid epidermal renewal with predictable volume of coagulation in dermis related to the length of the needle and the power used. Coagulation of capillaries during treatment allows a dry treatment field. The predictability of the effect and minimal downtime may offer a significant advantage over treatments with ablative fractional lasers of insulated RF microneedles.
Characterization of polymeric microneedle arrays for transdermal drug delivery.
Demir Yusuf K,Akan Zafer,Kerimoglu Oya
Microfabrication of dissolvable, swellable, and biodegradable polymeric microneedle arrays (MNs) were extensively investigated based in a nano sensitive fabrication style known as micromilling that is then combined with conventional micromolding technique. The aim of this study was to describe the polymer selection, and optimize formulation compounding parameters for various polymeric MNs. Inverse replication of micromilled master MNs reproduced with polydimethylsiloxane (PDMS), where solid out of plane polymeric MNs were subsequently assembled, and physicochemically characterized. Dissolvable, swellable, and biodegradable MNs were constructed to depth of less than 1 mm with an aspect ratio of 3.6, and 1/2 mm of both inter needle tip and base spacing. Micromolding step also enabled to replicate the MNs very precisely and accurate. Polymeric microneedles (MN) precision was ranging from ± 0.18 to ± 1.82% for microneedle height, ± 0.45 to ± 1.42% for base diameter, and ± 0.22 to ± 0.95% for interbase spacing. Although dissolvable sodium alginate MN showed less physical robustness than biodegradable polylactic-co-glycolic acid MN, their thermogravimetric analysis is of promise for constructing these polymeric types of matrix devices.
Integrated slanted microneedle-LED array for optogenetics.
Kwon Ki Yong,Khomenko Anton,Haq Mahmoodul,Li Wen
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference
This paper presents a three-dimensional (3-D) flexible micro light emitting diode (μ-LED) array for selective optical stimulation of cortical neurons. The array integrated individually addressable μ-LED chips with slanted polymer-based microneedle waveguides to allow precise light delivery to multiple cortical layers simultaneously. A droplet backside exposure method was developed to monolithically fabricate slanted microneedles on a single polymer platform. A wafer-level assembly technique was demonstrated, which permits large-scale, high-density system integration. The electrical, optical, thermal, and mechanical properties of the 3-D slanted microneedle-LED array were characterized experimentally.
Dose sparing and enhanced immunogenicity of inactivated rotavirus vaccine administered by skin vaccination using a microneedle patch.
Moon Sungsil,Wang Yuhuan,Edens Chris,Gentsch Jon R,Prausnitz Mark R,Jiang Baoming
Skin immunization is effective against a number of infectious diseases, including smallpox and tuberculosis, but is difficult to administer. Here, we assessed the use of an easy-to-administer microneedle (MN) patch for skin vaccination using an inactivated rotavirus vaccine (IRV) in mice. Female inbred BALB/c mice in groups of six were immunized once in the skin using MN coated with 5 μg or 0.5 μg of inactivated rotavirus antigen or by intramuscular (IM) injection with 5 μg or 0.5 μg of the same antigen, bled at 0 and 10 days, and exsanguinated at 28 days. Rotavirus-specific IgG titers increased over time in sera of mice immunized with IRV using MN or IM injection. However, titers of IgG and neutralizing activity were generally higher in MN immunized mice than in IM immunized mice; the titers in mice that received 0.5 μg of antigen with MN were comparable or higher than those that received 5 μg of antigen IM, indicating dose sparing. None of the mice receiving negative-control, antigen-free MN had any IgG titers. In addition, MN immunization was at least as effective as IM administration in inducing a memory response of dendritic cells in the spleen. Our findings demonstrate that MN delivery can reduce the IRV dose needed to mount a robust immune response compared to IM injection and holds promise as a strategy for developing a safer and more effective rotavirus vaccine for use among children throughout the world.
Tower microneedle via reverse drawing lithography for innocuous intravitreal drug delivery.
Lee Chang Yeol,Lee Kwang,You Yong Sung,Lee Sung Ho,Jung Hyungil
Advanced healthcare materials
The "tower microneedle" (TM) via reverse drawing lithography for intravitreal injection by fabricating a long hollow microneedle on the blunt hypodermic needle: The hollow hole between the microneedle and hypodermic needle is aligned concentrically, and fifteen degree bevel angle is introduced to TM by laser cutting to achieve intravitreal injection with minimal damage to eye tissue.
Assessment of treatment efficacy and sebosuppressive effect of fractional radiofrequency microneedle on acne vulgaris.
Lee Kyung Real,Lee Eo Gin,Lee Hee Jung,Yoon Moon Soo
Lasers in surgery and medicine
BACKGROUND AND OBJECTIVE:A minimally invasive fractional radiofrequency microneedle (FRM) device has been used in skin rejuvenation and acne scars, and a recent pilot study demonstrated the positive therapeutic effect on acne. We evaluated the efficacy of FRM device for acne vulgaris in Asians and conducted objective measurement to assess its effect on sebum production. PATIENTS AND METHODS:Twenty Korean patients with acne vulgaris received a single full-face FRM treatment. Outcome assessments included standardized photography, physician's global assessment, patient's satisfaction scores, acne lesion count, and objective measurements of casual sebum level (CSL) and sebum excretion rate (SER). They were evaluated at baseline and 2, 4, 8 weeks after the treatment. RESULTS:After a single FRM treatment, the CSL and the SER showed 30-60% and 70-80% reduction, respectively, at week 2 (P < 0.01), and remained below the baseline level until week 8. Physician's global improvement scores for acne severity and acne lesion count also revealed clinical improvement with maximum efficacy at week 2, but returned to the baseline in most patients by week 8. Patients' satisfaction scores (0-4) were above 2 on average, and adverse effects were minimal. CONCLUSION:This prospective study demonstrated the sebosuppressive effect from a single FRM treatment, but its therapeutic efficacy in acne requires further evaluation.
Sodium alginate microneedle arrays mediate the transdermal delivery of bovine serum albumin.
Demir Yusuf K,Akan Zafer,Kerimoglu Oya
BACKGROUND:The "poke and release" strategy for the delivery of macromolecules using polymeric microneedle (MN) is of great importance because it eliminates microneedle reuse, the risks of biohazardous sharps and cross contamination, and it requires no special disposal mechanism. The main objective of this study was the determination of the stability and delivery of bovine serum albumin (BSA) that was transported across human skin via sodium alginate (SA) microneedle arrays (MNs) and SA needle free patches using two different analytical methods. METHODOLOGY AND FINDINGS:The capability of two analytical methods, the bicinchoninic acid (BCA) assay and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), to precisely detect and quantify BSA within different types of polymeric MNs was assessed. The ex vivo protein release of BSA across dermatomed human abdominal skin from 10 w/w SA MNs was compared to that from needle-free patches using Franz diffusion cells. The developed applicator was mechanically characterized using a Texture Analyzer. The patch mold and its components were fabricated using a rapid prototyping machine. CONCLUSIONS/SIGNIFICANCE:The BCA method was able to precisely detect BSA that had been loaded into SA MNs. However, the use of SDS-PAGE as the analytical method resulted in significantly different amounts of BSA recovered from differently conditioned polymeric MNs. The permeation of BSA across dermatomed human abdominal skin by SA MNs, which were composed of 100 pyramidal needles, increased by approximately 15.4 fold compared to the permeation obtained with SA needle-free patches. The ease of use of the applicator during the release studies was also demonstrated, as was its mechanical characterization.
Effect of formulation pH on transport of naltrexone species and pore closure in microneedle-enhanced transdermal drug delivery.
Ghosh Priyanka,Brogden Nicole K,Stinchcomb Audra L
Microneedle-enhanced transdermal drug delivery greatly improves the subset of pharmacologically active molecules that can be transported across the skin. Formulation pH plays an important role in all drug delivery systems; however, for transdermal delivery it becomes specifically significant since a wide range of pH values can be exploited for patch formulation as long as it does not lead to skin irritation or sensitization issues. Wound healing literature has shown significant pH effects on barrier recovery. Stability and solubility of the drug, and thus transport across skin, are all affected by formulation pH. The current study examined the role of ionization state of the drug naltrexone on transdermal flux and permeability across microneedle treated skin, as compared to intact skin. Impedance spectroscopy was done in pigs in vivo to assess the role of formulation pH on the rate of micropore closure under the influence of three different pH conditions. The data indicated that while there was significant advantage of using a lower pH formulation in terms of total transport across microneedle treated skin, the pH however did not have any significant effect on the rate of micropore closure beyond the first 24 h.
Fabrication of a microneedle/CNT hierarchical micro/nano surface electrochemical sensor and its in-vitro glucose sensing characterization.
Yoon Youngsam,Lee Gil S,Yoo Koangki,Lee Jeong-Bong
Sensors (Basel, Switzerland)
We report fabrication of a microneedle-based three-electrode integrated electrochemical sensor and in-vitro characterization of this sensor for glucose sensing applications. A piece of silicon was sequentially dry and wet etched to form a 15 × 15 array of tall (approximately 380 µm) sharp silicon microneedles. Iron catalyst was deposited through a SU-8 shadow mask to form the working electrode and counter electrode. A multi-walled carbon nanotube forest was grown directly on the silicon microneedle array and platinum nano-particles were electrodeposited. Silver was deposited on the Si microneedle array through another shadow mask and chlorinated to form a Ag/AgCl reference electrode. The 3-electrode electrochemical sensor was tested for various glucose concentrations in the range of 3~20 mM in 0.01 M phosphate buffered saline (PBS) solution. The sensor's amperometric response to the glucose concentration is linear and its sensitivity was found to be 17.73 ± 3 μA/mM-cm2. This microneedle-based sensor has a potential to be used for painless diabetes testing applications.
Gene Silencing in Skin After Deposition of Self-Delivery siRNA With a Motorized Microneedle Array Device.
Hickerson Robyn P,Wey Winston C,Rimm David L,Speaker Tycho,Suh Susie,Flores Manuel A,Gonzalez-Gonzalez Emilio,Leake Devin,Contag Christopher H,Kaspar Roger L
Molecular therapy. Nucleic acids
Despite the development of potent siRNAs that effectively target genes responsible for skin disorders, translation to the clinic has been hampered by inefficient delivery through the stratum corneum barrier and into the live cells of the epidermis. Although hypodermic needles can be used to transport siRNA through the stratum corneum, this approach is limited by pain caused by the injection and the small volume of tissue that can be accessed by each injection. The use of microneedle arrays is a less painful method for siRNA delivery, but restricted payload capacity limits this approach to highly potent molecules. To address these challenges, a commercially available motorized microneedle array skin delivery device was evaluated. This device combines the positive elements of both hypodermic needles and microneedle array technologies with little or no pain to the patient. Application of fluorescently tagged self-delivery (sd)-siRNA to both human and murine skin resulted in distribution throughout the treated skin. In addition, efficient silencing (78% average reduction) of reporter gene expression was achieved in a transgenic fluorescent reporter mouse skin model. These results indicate that this device effectively delivers functional sd-siRNA with an efficiency that predicts successful clinical translation.Molecular Therapy-Nucleic Acids (2013) 2, e129; doi:10.1038/mtna.2013.56; published online 22 October 2013.
Targeting the skin for microneedle delivery of influenza vaccine.
Koutsonanos Dimitrios G,Compans Richard W,Skountzou Ioanna
Advances in experimental medicine and biology
Influenza infection represents a major socioeconomic burden worldwide. Skin represents a new target that has gained much attention in recent years for delivery of influenza vaccine as an alternative to the conventional intramuscular route of immunization. In this review we describe different microneedle vaccination approaches used in vivo, including metal and dissolving microneedle patches that have demonstrated promising results. Additionally we analyze the immunological basis for microneedle skin immunization and targeting of the skin's dense population of antigen presenting cells, their role, characterization, and function. Additionally we analyze the importance of inflammatory signaling in the skin after microneedle delivery.
Use of microneedle array devices for continuous glucose monitoring: a review.
El-Laboudi Ahmed,Oliver Nick S,Cass Anthony,Johnston Desmond
Diabetes technology & therapeutics
Microneedle array devices provide the opportunity to overcome the barrier characteristics of the outermost skin layer, the stratum corneum. This novel technology can be used as a therapeutic tool for transdermal drug delivery, including insulin, or as a diagnostic tool providing access to dermal biofluids, with subsequent analysis of its contents. Over the last decade, the use of microneedle array technology has been the focus of extensive research in the field of transdermal drug delivery. More recently, the diagnostic applications of microneedle technology have been developed. This review summarizes the existing evidence for the use of microneedle array technology as biosensors for continuous monitoring of the glucose content of interstitial fluid, focusing also on mechanics of insertion, microchannel characteristics, and safety profile.
Skin rejuvenation by microneedle fractional radiofrequency and a human stem cell conditioned medium in Asian skin: a randomized controlled investigator blinded split-face study.
Seo Kyu Young,Kim Dong Hyun,Lee Sang Eun,Yoon Moon Soo,Lee Hee Jung
Journal of cosmetic and laser therapy : official publication of the European Society for Laser Dermatology
BACKGROUND AND OBJECTIVES:For skin rejuvenation, microneedle fractional radiofrequency (RF) is a recently developed minimally invasive method for delivering RF energy directly into the skin using microneedle. Additionally, the use of growth factors in skin rejuvenation is emerging as a novel anti-aging treatment. We evaluated efficacy and safety of microneedle fractional RF for skin rejuvenation, and furthermore the synergistic effect of stem cell conditioned medium, composed of a large number of growth factors and cytokines. MATERIALS AND METHODS:Fifteen females were included for a split-face comparative study with a blinded response evaluation. One side of each subject's face was treated with fractional RF alone, and the other side was treated with fractional RF plus stem cell conditioned medium. Patients received 3 sessions of treatment at 4-week intervals. RESULTS:All patients showed clinical improvement on physician's global assessment and patient satisfaction scores on both sides of their faces. Among objective biophysical measurements, improvement in hydration, melanin, erythema index and especially skin roughness was noticed. Stem cell conditioned medium provided a synergistic effect on improvement of skin roughness, which was statistically significant (p <0.05). Histologic examination revealed marked increase in dermal thickness and dermal collagen content. Side effects were minimal. CONCLUSION:Microneedle fractional RF is a safe and effective skin rejuvenation method, and the better results may be expected when combined with stem cell conditioned medium.
Immunological effects of microneedle-mediated insulin delivery: preliminary rat studies.
Qiu Yuqin,Gao Yunhua,Zhang Suohui,Guo Lei,Chen Jianmin,Xu Bai
International journal of pharmaceutics
The objective of the present study is to compare the immunogenicity of insulin by microneedle-mediated intradermal delivery or subcutaneous injection. Female and male rats were treated with insulin by either microneedle-mediated intradermal delivery or subcutaneous injection twice a week for 4 weeks. A control group without insulin administration was also studied. Human anti-insulin antibody (AIA) levels were measured by radioimmunoassay (RIA) before starting insulin treatment and after that within 20 weeks. The male rats did not induce positive AIA levels, and there was no significant difference between all male groups. In contrast, in female rats the AIA levels were significantly higher in microneedle group compared with injection group, and lasted from 6 to 20 weeks after starting insulin treatment. The increased immunogenicity of insulin delivery by microneedle might be due to the large number of immune cells in skin.
Development of a novel therapeutic approach using a retinoic acid-loaded microneedle patch for seborrheic keratosis treatment and safety study in humans.
Hiraishi Yasuhiro,Hirobe Sachiko,Iioka Hiroshi,Quan Ying-Shu,Kamiyama Fumio,Asada Hideo,Okada Naoki,Nakagawa Shinsaku
Journal of controlled release : official journal of the Controlled Release Society
Seborrheic keratosis is one of the most common skin benign tumors in humans with a high occurrence rate of 80%-100% in people > 50 years of age; however, its pathogenesis is still unclear. The standard treatment includes cryotherapy and laser surgery for physically removing lesions. Drug therapy for this condition has not been well established. We aimed to evaluate the use of all-trans retinoic acid (ATRA)-loaded microneedle (MN) patches as a simple, alternative therapeutic option to traditional surgical treatments. This therapeutic strategy was designed to induce the proliferation of basal keratinocytes and accelerate stratum corneum turnover, leading to the lesion falling off the surface of the skin. The MN patch induced epidermal hyperplasia and marked expression of heparin-binding epidermal growth factor-like growth factor mRNA and protein corresponding to ATRA activity in the skin of HR-1 hairless mice. The acceleration of stratum corneum turnover was also observed by the dansyl chloride method. The skin irritation study in mice and safety study in humans support the safety findings of our study. Overall, MN patches can offer an effective and safe means of ATRA delivery into the skin, and the ATRA-loaded MN patch appears to be an effective pharmaceutical product providing a novel therapeutic option for seborrheic keratosis.
Tower microneedle minimizes vitreal reflux in intravitreal injection.
Lee Chang Yeol,You Yong Sung,Lee Sung Ho,Jung Hyungil
Intravitreal injection is widely used for easy control of drug levels in posterior segment of the eye by injecting the drug directly with hypodermic needles. Patients, however, often experience complications from intravitreal injection due to repeated injections, increased intraocular pressure, and infection. In addition, injected drug reflux after intravitreal injection makes it challenging to maintain predetermined drug dose due to the drug loss through backward effusions. Here, we described that the Tower Microneedle can reduce initial reflux and bleb formation due to its smaller outer diameter compared to a traditional hypodermic needle. Furthermore, we use phenylephrine hydrochloride for pupil expansion and demonstrated that Tower Microneedle induced similar pupil expansions using only half the drug volume, in the same period of time, compared to the 31 Gauge hypodermic needle. Consequently, Tower Microneedle achieves the same therapeutic effect in the vitreous body using fewer drugs than a traditional hypodermic needle due to the decreased backward drug effusion. Tower Microneedle described herein holds great promise for intravitreal injection with less reflux and lower drug dosage.
A simple method of microneedle array fabrication for transdermal drug delivery.
Kochhar Jaspreet Singh,Goh Wei Jiang,Chan Sui Yung,Kang Lifeng
Drug development and industrial pharmacy
The outermost layer of skin, stratum corneum, being lipophilic limits the passive transport of hydrophilic and large molecular weight drugs. Microfabrication technology has been adapted to fabricate micron scale needles, which are minimally invasive, yet able to deliver the drugs across this barrier layer. In this study, we fabricated microneedles from a biocompatible polymer, namely, poly (ethylene glycol) diacrylate. A simple lithographical approach was developed for microneedle array fabrication. Several factors including polymerization time, ultraviolet light intensity and distance from light source were studied for their effects on microneedle formation. The microneedle length and tip diameter can be controlled by varying these factors. The microneedles were shown to be able to penetrate cadaver pig skin. Model drug rhodamine B was encapsulated in the range of 50 µg to 450 µg per microneedle array. The fabricated microneedles containing rhodamine B increased the permeability by four times than the control. Altogether, we demonstrated that the microneedle arrays can be fabricated through a simple single-step process and needles were mechanically strong to penetrate skin, increasing the permeability of encapsulated drug through skin.
Hepatitis B DNA vaccine-polycation nano-complexes enhancing immune response by percutaneous administration with microneedle.
Yin Dongfeng,Liang Wenqing,Xing Shuxing,Gao Zhixiang,Zhang Wei,Guo Zhili,Gao Shen
Biological & pharmaceutical bulletin
Percutaneous immune method is becoming an attractive alternative for DNA vaccine as a lot of antigen presenting cells are existed in the viable epidermis. However, due to the barrier function of stratum corneum, it would be hard for DNA vaccine to reach the viable epidermis of the skin. In order to deliver the DNA vaccine successfully cross the stratum corneum, pentagram silicon microneedle array was prepared in this study, and fluorescently labeled nanoparticle was taken as the model to observe the situation inside the skin processed by microneedle. Via microneedle nanoparticles could enter the skin through the micro-channel (diameter about 20-30 µm) and its amount is greatly larger than that enter though the hair follicle of intact skin. A new type of gene vector Pluronic P123-modified polyethyleneimine (P123-PEI) was synthesized by high molecular weight polyethylenimine and Pluronic P123 with the molar ratio of 1 : 1 to take the advantage of P123-PEI as low cytotoxicity and high transfection efficiency. Mice were immunized percutaneously with Hepatitis B DNA vaccine/P123-PEI nano-complexes by microneedle. The humoral and cellular immunity generated in percutaneously immunized mice through microneedle array by Hepatitis B DNA vaccine/P123-PEI nano-complex was significantly higher than that of DNA vaccine intramuscular administration.
Dissolving and biodegradable microneedle technologies for transdermal sustained delivery of drug and vaccine.
Hong Xiaoyun,Wei Liangming,Wu Fei,Wu Zaozhan,Chen Lizhu,Liu Zhenguo,Yuan Weien
Drug design, development and therapy
Microneedles were first conceptualized for drug delivery many decades ago, overcoming the shortages and preserving the advantages of hypodermic needle and conventional transdermal drug-delivery systems to some extent. Dissolving and biodegradable microneedle technologies have been used for transdermal sustained deliveries of different drugs and vaccines. This review describes microneedle geometry and the representative dissolving and biodegradable microneedle delivery methods via the skin, followed by the fabricating methods. Finally, this review puts forward some perspectives that require further investigation.
Host responses in human skin after conventional intradermal injection or microneedle administration of virus-like-particle influenza vaccine.
Pearton Marc,Pirri Daniela,Kang Sang-Moo,Compans Richard W,Birchall James C
Advanced healthcare materials
Miniaturized microneedle devices are being developed for painlessly targeting vaccines to the immune cell populations in skin. As skin immunization studies are generally restricted to animal models however, where skin architecture and immunity is greatly different to human, surprisingly little is known about the local human response to intradermal (ID) vaccines. Here surgically excised human skin is used to explore for the first time the complex molecular and cellular host responses to a candidate influenza vaccine comprising nanoparticulate virus-like-particles (VLPs), administered via conventional hypodermic injection or reduced scale microneedles. Responses at the molecular level are determined by microarray analysis (47,296 discrete transcripts) and validated by quantitative PCR (96 genes). Cellular response is probed through monitoring migration of dendritic cells in viable skin tissue. Gene expression mapping, ontological analysis, and qPCR reveal up-regulation of a host of genes responsible for key immunomodulatory processes and host viral response, including cell recruitment, activation, migration, and T cell interaction following both ID and microneedle injection of VLPs; the response from the microneedles being more subtle. Significant morphological and migratory changes to skin dendritic cells are also apparent following microneedle VLP delivery. This is the first study displaying the global, multifaceted immunological events that occur at the site of vaccine deposition in human skin and will subsequently influence the degree and nature of innate and adaptive immune responses. An increased understanding of the detailed similarities and differences in response against antigen administered via different delivery modalities will inform the development of improved vaccines and vaccine delivery systems.
The combination of microneedles with electroporation and sonophoresis to enhance hydrophilic macromolecule skin penetration.
Petchsangsai Maleenart,Rojanarata Theerasak,Opanasopit Praneet,Ngawhirunpat Tanasait
Biological & pharmaceutical bulletin
The objective of the present work was to investigate the effects of 3 combinatorial techniques (microneedle (MN), electroporation (EP), and sonophoresis (SN)) on the in vitro skin permeation of the hydrophilic macromolecular compound fluorescein isothiocyanate-dextran (FD-4; molecular weight (MW) 4.4 kDa). Assessment of the in vitro skin permeation of FD-4 was performed in porcine skin. MN, EP, and SN were used as physical enhancement methods, given the potential of their various mechanisms. The total cumulative amount of FD-4 that permeated through treated skin using 2 or 3 combined methods, i.e., MN+EP, MN+SN, EP+SN, and MN+EP+SN, was investigated. Microconduits created by MN alone and in combination with the other techniques were observed under confocal laser scanning microscopy (CLSM). The histology of the treated skin was examined. In vitro skin permeation experiments revealed that the total cumulative amount of FD-4 that permeated porcine skin using 3 combined techniques (MN+EP+SN) was greater than the amount observed using a single method or 2 combinations (MN+EP, MN+SN, SN+EP). The histological images indicate no noticeable damage in the skin treated with all of the enhancement methods. These results suggest that MN+EP+SN may serve as a potentially effective combination strategy to transdermally deliver various hydrophilic macromolecules without causing structural alterations or skin damage.
A special issue on reviews in nanomedicine, drug delivery and vaccine development.
Nalwa Hari Singh
Journal of biomedical nanotechnology
This thematic special issue of the Journal of Biomedical Nanotechnology focused on the "Reviews in Nanomedicine, Drug Delivery and Vaccine Development" contains 30 state-of-the-art review articles covering recent advances, trends and future directions emphasized on nanoparticle-based new strategies for diagnosis and cancer phototherapies, nanomedicine, nucleic acid-based nanocarriers, gene and drug delivery systems, tuberculosis mucosal and H5N1 influenza vaccines, drug-loaded electrospun polymer nanofibers, microneedle technology for insulin delivery for the treatment of insulin-dependent diabetes mellitus, RNA-based therapies, nanotoxicity and biosafety of nanomaterials to environment and human health.
Fabrication of carbon nanotube-polyimide composite hollow microneedles for transdermal drug delivery.
Lyon Bradley J,Aria Adrianus I,Gharib Morteza
We introduce a novel method for fabricating hollow microneedles for transdermal drug delivery using a composite of vertically-aligned carbon nanotubes and polyimide. Patterned bundles of carbon nanotubes are used as a porous scaffold for defining the microneedle geometry. Polyimide resin is wicked through the carbon nanotube scaffold to reinforce the structure and provide the prerequisite strength for achieving skin penetration. The high aspect ratio and bottom-up assembly of carbon nanotubes allow the structure of the microneedles to be created in a single step of nanotube fabrication, providing a simple, scalable method for producing hollow microneedles. To demonstrate the utility of these microneedles, liquid delivery experiments are performed. Successful delivery of aqueous methylene blue dye into both hydrogel and swine skin in vitro is demonstrated. Electron microscopy images of the microneedles taken after delivery confirm that the microneedles do not sustain any structural damage during the delivery process.
Safety and feasibility of adjunctive dexamethasone infusion into the adventitia of the femoropopliteal artery following endovascular revascularization.
Owens Christopher D,Gasper Warren J,Walker Joy P,Alley Hugh F,Conte Michael S,Grenon S Marlene
Journal of vascular surgery
OBJECTIVE:Restenosis following endovascular treatment of the femoropopliteal segment is associated with the inflammatory response produced in the artery wall at the time of the procedure. Although local drug delivery to the superficial femoral and popliteal arteries promises improved patency, data are currently limited. We hypothesized that improved percutaneous delivery of an anti-inflammatory compound into the adventitia of the femoropopliteal at the time of endovascular treatment would be safe, feasible, and decrease the inflammatory response. METHODS:This was a prospective, investigator-initiated, phase I, first-in-man study testing the safety and feasibility of percutaneous adventitial delivery of dexamethasone. Following successful intervention, an adventitial microinfusion catheter was advanced over a 0.014-inch wire to the treated segment. Its microneedle (0.9 mm long × 140-μm diameter) was deployed into the adventitia to deliver dexamethasone (4 mg/mL) mixed with contrast agent (80:20 ratio), providing fluoroscopic visualization. The primary safety outcome measure was freedom from vessel dissection, thrombosis, or extravasation while the primary efficacy outcome was duplex-determined binary restenosis defined as a peak systolic velocity ratio >2.5. RESULTS:Twenty patients with Rutherford clinical category 2-5 enrolled in this study. The mean age was 66, and 55% had diabetes mellitus. Treated lesion length was 8.9 ± 5.3 cm, and 50% were chronic total occlusions. Eighty percent of treated lesions were in the distal superficial femoral or popliteal arteries. All lesions were treated by balloon angioplasty with provisional stenting (n = 6) for suboptimal result. Three patients were treated with atherectomy as well. A mean of 1.6 ± 1.1 mg (0.5 ± 0.3 mL) of dexamethasone sodium phosphate was injected per centimeter of lesion length. In total, a mean of 12.1 ± 6.1 mg of dexamethasone was injected per patient. The mean number of injections required per lesion was 3.0 ± 1.3 cm, minimum one and maximum six injections. There was 100% technical success of drug delivery and no procedural or drug-related adverse events. The mean Rutherford score decreased from 3.1 ± .7 (median, 3.0) preoperatively to .5 ± .7 at 6 months (median, 0.0; P < .00001). Over this same time interval, the index leg ankle-brachial index increased from .68 ± .15 to .89 ± .19 (P = .0003). The preoperative C-reactive protein in this study was 6.9 ± 8.5 indicating severe baseline inflammation, which increased to 14.0 ± 23.1 mg/L (103% increase) at 24 hours following the procedure. However, this increase did not reach statistical significance of P = .14. Two patients met the primary efficacy end point of loss of primary patency by reoccluding their treated segment of the index lesion during the follow-up period. CONCLUSIONS:Adventitial drug delivery via a microinfusion catheter is a safe and feasible alternative to intimal-based methods for adjunctive treatment in the femoropopliteal segment. The 6-month preliminary results suggest perivascular dexamethasone treatment may improve outcomes following angioplasty to the femoral and popliteal arteries, and support further clinical investigation of this approach.
Particle-stabilized emulsion droplets for gravity-mediated targeting in the posterior segment of the eye.
Kim Yoo C,Edelhauser Henry F,Prausnitz Mark R
Advanced healthcare materials
This study tests the hypothesis that high-density particle-stabilized emulsion droplets (PEDs) can be designed to use gravity to target specific locations in the eye via suprachoroidal space injection. PEDs contain a core of high-density perfluorodecalin measuring ≤35 μm in diameter surrounded and stabilized by fluorescein-tagged, polystyrene nanoparticles that simulate polymeric drug carriers. A hollow microneedle infuses PEDs into the suprachoroidal space of rabbit eyes in vivo, which are later dissected and imaged to quantify distribution of fluorescent nanoparticles within the suprachoroidal space. With cornea oriented upward, such that gravity should move PEDs toward the back of the eye, up to 50% of nanoparticles are in the most posterior quadrant near the macula immediately after injection and 5 d later. With cornea oriented downward, to promote PED movement toward the front of the eye, approximately 60% of injected nanoparticles are targeted to the most anterior quadrant of the posterior segment near ciliary body. Injection of approximately neutral-density particles of the same size shows approximately equal distribution throughout the posterior segment. This study demonstrates for the first time that high-density PEDs can be used to deliver nanoparticles to specific locations in the back of the eye, including targeted delivery to the macula.
Intradermal and virosomal influenza vaccines for preventing influenza hospitalization in the elderly during the 2011-2012 influenza season: a comparative effectiveness study using the Valencia health care information system.
Puig-Barberà J,Natividad-Sancho A,Calabuig-Pérez J,Lluch-Rodrigo J A,Pastor-Villalba E,Martínez-Úbeda S,Díez-Domingo J
BACKGROUND:The use of intradermal vaccination or virosomal vaccines could increase protection against influenza among the vulnerable population of older adults. Studies assessing the comparative effectiveness of these two influenza vaccine types in this age group are lacking. METHODS:We conducted a retrospective cohort study to estimate the comparative effectiveness of intradermal seasonal trivalent-influenza vaccine (TIV) delivered by a microneedle injection system and a virosomal-TIV intramuscularly delivered for prevention of influenza hospitalization in non-institutionalized adults aged ≥65 years. We obtained administrative data on immunization status and influenza hospitalization for the 2011-2012 influenza season, and used Cox regression models to assess comparative effectiveness. We estimated crude and adjusted (age, sex, comorbidity, pharmaceutical claims, recent pneumococcal vaccination and number of hospitalizations for all causes other than influenza between the previous and current influenza seasons) hazard ratios (HR). RESULTS:Overall, 164,021 vaccinated subjects were evaluated. There were 127 hospitalizations for influenza among 62,058 subjects, contributing 914,740 person-weeks at risk in the virosomal-TIV group, and 133 hospitalizations for influenza among 101,963 subjects, contributing 1,504,570 person-weeks at risk in the intradermal-TIV group. The crude HR of intradermal-TIV relative to virosomal-TIV was 0.64 (95% confidence interval (CI): 0.50-0.81), and the adjusted Cox estimated HR was 0.67 (95% CI: 0.52-0.85). CONCLUSIONS:During the 2011-2012 influenza season the risk of hospitalization for influenza was reduced by 33% in non-institutionalized elderly adults who were vaccinated with intradermal-TIV compared with virosomal-TIV.
Wound healing potential of antibacterial microneedles loaded with green tea extracts.
Park So Young,Lee Hyun Uk,Lee Young-Chul,Kim Gun Hwa,Park Edmond Changkyun,Han Seung Hyun,Lee Jeong Gyu,Choi Saehae,Heo Nam Su,Kim Dong Lak,Huh Yun Suk,Lee Jouhahn
Materials science & engineering. C, Materials for biological applications
This study evaluates the utility of an antibacterial microneedle composed of green tea (GT) extract and hyaluronic acid (HA), for the efficient delivery of GT. These microneedles have the potential to be a patient-friendly method for the conventional sustained release of drugs. In this study, a fabrication method using a mold-based technique to produce GT/HA microneedles with a maximum area of ~50mm(2) with antibacterial properties was used to manufacture transdermal drug delivery systems. Fourier transform infrared (FTIR) spectrometry was carried out to observe the potential modifications in the microneedles, when incorporated with GT. The degradation rate of GT in GT/HA microneedles was controlled simply by adjusting the HA composition. The effects of different ratios of GT in the HA microneedles were determined by measuring the release properties. In HA microneedles loaded with 70% GT (GT70), a continuous higher release rate was sustained for 72h. The in vitro cytotoxicity assays demonstrated that GT/HA microneedles were not generally cytotoxic to Chinese hamster ovary cells (CHO-K1), human embryonic kidney cells (293T), and mouse muscle cells (C2C12), which were treated for 12 and 24h. Antimicrobial activity of the GT/HA microneedles was demonstrated by ~95% growth reduction of gram negative [Escherichia coli (E. coli), Pseudomonas putida (P. putida), and Salmonella typhimurium (S. typhimurium)] and gram positive bacteria [Staphylococcus aureus (S. Aureus) and Bacillus subtilis (B. subtilis)], with GT70. Furthermore, GT/HA microneedles reduced bacterial growth of infected wound sites in the skin and improved wound healing process of skin in rat model.
Self-setting bioceramic microscopic protrusions for transdermal drug delivery.
Cai Bing,Xia Wei,Bredenberg Susanne,Engqvist Håkan
Journal of materials chemistry. B
Microneedle (MN) technology offers both an efficient and a minimally invasive transdermal drug delivery strategy. The current MNs, made of silicon and metal, have poor biocompatibility and low drug loading, while the polymer MNs have some constraints related to mechanical strength and storage conditions. In this study, self-setting bioceramics were explored as substitutes for the current MN materials for the first time. Self-setting bioceramic microneedles were fabricated using a master mold by a procedure under mild conditions, which could minimize the drug degradation during fabrication and also facilitates a higher drug loading capability than the other current ceramic microneedles. The drug release and mechanical strength were correlated with the microstructure and porosity of the needles. As observed by SEM and microCT, the ceramic paste could fully fill the geometry of the mould and was cured into an array of micro-sized needles. The drug release study showed that the release rate from this type of MN array could be controlled by the bulk surface area, porosity and resorption rate of the ceramic needles. Applying the MNs to porcine skin indicated that the needles were able to pierce the stratum corneum of the skin. We successfully prepared the bioceramic needles that have high mechanical strength and are resorbable, which can promote safe, efficient and successful transdermal drug delivery.
Damage of zona pellucida reduces the developmental potential and quality of porcine circovirus type 2-infected oocytes after parthenogenetic activation.
Zhao Haijing,Ji Qianqian,Zhao Guangyin,Song Zhenwei,Du Baozhu,Nie Yu,Chen Yaosheng,Cong Peiqing
The present aimed to study if porcine circovirus type 2 (PCV2), which adhered to zona pellucida (ZP), was able to enter mature porcine oocytes with intact and damaged ZP. Four groups, including uninfected ZP-intact oocytes (UOZI), uninfected ZP-damaged oocytes (UOZD), PCV2-infected ZP-intact oocytes (POZI), and PCV2-infected ZP-damaged oocytes (POZD) were studied. The oocytes were incubated with 1 mL minimum essential medium, containing 3.1 × 10(8) copies of PCV2 DNA for 1 hour. Mechanical procedure of the insertion by microneedle induced injuries to the ZP of porcine oocytes. At the blastocyst stage, the percentage of PCV2-infected embryos and the ratio of viral antigen-positive cells per embryo were determined by indirect immunofluorescence. To assess the effect of ZP injury on the developmental competence and quality of porcine PCV2-infected oocytes after parthenogenetic activation, blastocyst formation rates and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling staining were analyzed. Moreover, real-time polymerase chain reaction was used to evaluate the expression of genes related to apoptosis and pluripotency at different developmental stages. The results of indirect immunofluorescence showed that only POZD group presented PCV2-infected embryos and viral-positive cells. The blastocyst rate of POZD group dropped down to approximately half of POZI group's (7.1 ± 1.5 vs. 14.5 ± 3.3). At the blastocyst stage, ZP injury increased apoptotic index of PCV2-infected embryos. The relative expression levels of Caspase 3 were higher in POZD group than the ones in POZI group at the two- and four-cell stages (not statistically significant). Compared with the one in POZI group, the ratio of antiapoptotic Bcl-xl gene to proapoptotic Bax gene, an indicator of the ability to resist apoptosis, was lower in POZD group at the one-cell stage, but higher at the two- and four-cell stages. Expression levels of Oct4 and Nanog associated with pluripotency were lower in POZD group than the ones in POZI group at the morula stage (not statistically significant). Noteworthily, the expression of Nanog was significantly lower in POZD group versus POZI group (P < 0.05), whereas relative expression of Oct4 was significantly higher in the former at the blastocyst stage (P < 0.01). In conclusion, PCV2, which attached to ZP, was able to enter mature porcine oocytes with damaged ZP and subsequently reduced the developmental competence and quality of the oocytes after parthenogenetic activation.
Efficacy of microneedling plus human stem cell conditioned medium for skin rejuvenation: a randomized, controlled, blinded split-face study.
Lee Hee Jung,Lee Eo Gin,Kang Sangjin,Sung Jong-Hyuk,Chung Hyung-Min,Kim Dong Hyun
Annals of dermatology
BACKGROUND:The use of growth factors in skin rejuvenation is emerging as a novel anti-aging treatment. While the role of growth factors in wound healing is well established, their use in skin rejuvenation has only recently been to be studied and no controlled trials have been performed. OBJECTIVE:We evaluated the anti-aging effects of secretory factors of endothelial precursor cells differentiated from human embryonic stem cells (hESC-EPC) in Asian skin. METHODS:A total of 25 women were included in this randomized, controlled split-face study. The right and left sides of each participant's face were randomly allocated to hESC-EPC conditioned medium (CM) or saline. To enhance epidermal penetration, a 0.25-mm microneedle roller was used. Five treatment sessions were repeated at 2-week intervals. RESULTS:Physician's global assessment of pigmentation and wrinkles after treatment revealed statistically significant effects of microneedling plus hESC-EPC CM compared to microneedling alone (p<0.05). Skin measurements by Mexameter and Visiometer also revealed statistically significant effects of microneedling plus hESC-EPC CM on both pigmentation and wrinkles (p<0.05). The only minimal adverse event was mild desquamation in one participant. CONCLUSION:Secretory factors of hESC-EPC improve the signs of skin aging and could be a potential option for skin rejuvenation.
Proton flows across the plasma membrane in microperforated characean internodes: tonoplast injury and involvement of cytoplasmic streaming.
Bulychev Alexander A,Komarova Anna V
Microperforation of characean cell wall with a glass micropipette in the absence of the tonoplast impalement was found to cause rapid alkalinization of the apoplast by 2-3 pH units, which may rigidify the cell wall structure, thus protecting the cell from further injury. A similar but a deeper insertion of a microneedle, associated with piercing the tonoplast and with an action potential generation, led to a considerable delay in the apoplast alkalinization without affecting the amplitude of the eventual increase in pH. The retardation by the mechanically elicited action potential of the incision-mediated pH transients in the apoplast contrasted sharply to the enhancement of these pH transients by the action potential triggered electrically before the microperforation. Hence, the delay of the apoplast alkalinization was not related to basic ionic mechanisms of plant action potentials. Measurements of the vacuolar pH after mechanical elicitation of an action potential indicate that the tonoplast piercing was accompanied by leakage of protons from the vacuole into the cytoplasm, which may strongly acidify the cytoplasm around the wounded area, thus collapsing the driving force for H(+) influx from the medium into the cytoplasm. The lag period preceding the onset of external alkalinization was found linearly related to the duration of temporal cessation of cytoplasmic streaming. The results suggest that the delayed alkalinization of the apoplast in the region of tonoplast wounding reflects the localized recovery of the proton motive force across the plasmalemma during replacement of the acidic cytoplasm with fresh portions of unimpaired cytoplasm upon restoration of cytoplasmic streaming.
Coating solid dispersions on microneedles via a molten dip-coating method: development and in vitro evaluation for transdermal delivery of a water-insoluble drug.
Ma Yunzhe,Gill Harvinder S
Journal of pharmaceutical sciences
This study demonstrates for the first time the ability to coat solid dispersions on microneedles as a means to deliver water-insoluble drugs through the skin. Polyethylene glycol (PEG) was selected as the hydrophilic matrix, and lidocaine base was selected as the model hydrophobic drug to create the solid dispersion. First, thermal characterization and viscosity measurements of the PEG-lidocaine mixture at different mass fractions were performed. The results show that lidocaine can remain stable at temperatures up to ∼130°C and that viscosity of the PEG-lidocaine molten solution increases as the mass fraction of lidocaine decreases. Differential scanning calorimetry demonstrated that at lidocaine mass fraction less than or equal to 50%, lidocaine is well dispersed in the PEG-lidocaine mixture. Uniform coatings were obtained on microneedle surfaces. In vitro dissolution studies in porcine skin showed that microneedles coated with PEG-lidocaine dispersions resulted in significantly higher delivery of lidocaine in just 3 min compared with 1 h topical application of 0.15 g EMLA®, a commercial lidocaine-prilocaine cream. In conclusion, the molten coating process we introduce here offers a practical approach to coat water-insoluble drugs on microneedles for transdermal delivery.
Advanced materials and nanotechnology for drug delivery.
Yan Li,Yang Yang,Zhang Wenjun,Chen Xianfeng
Advanced materials (Deerfield Beach, Fla.)
Many biological barriers are of great importance. For example, stratum corneum, the outmost layer of skin, effectively protects people from being invaded by external microorganisms such as bacteria and viruses. Cell membranes help organisms maintain homeostasis by controlling substances to enter and leave cells. However, on the other hand, these biological barriers seriously restrict drug delivery. For instance, stratum corneum has a very dense structure and only allows very small molecules with a molecular weight of below 500 Da to permeate whereas most drug molecules are much larger than that. A wide variety of drugs including genes needs to enter cells for proper functioning but cell membranes are not permeable to them. To overcome these biological barriers, many drug-delivery routes are being actively researched and developed. In this research news, we will focus on two advanced materials and nanotechnology approaches for delivering vaccines through the skin for painless and efficient immunization and transporting drug molecules to cross cell membranes for high-throughput intracellular delivery.
Developments in human growth hormone preparations: sustained-release, prolonged half-life, novel injection devices, and alternative delivery routes.
Cai Yunpeng,Xu Mingxin,Yuan Minglu,Liu Zhenguo,Yuan Weien
International journal of nanomedicine
Since the availability of recombinant human growth hormone (rhGH) enabled the application of human growth hormone both in clinical and research use in the 1980s, millions of patients were prescribed a daily injection of rhGH, but noncompliance rates were high. To address the problem of noncompliance, numerous studies have been carried out, involving: sustained-release preparations, prolonged half-life derivatives, new injectors that cause less pain, and other noninvasive delivery methods such as intranasal, pulmonary and transdermal deliveries. Some accomplishments have been made and launched already, such as the Nutropin Depot microsphere and injectors (Zomajet, Serojet, and NordiFlex). Here, we provide a review of the different technologies and illustrate the key points of these studies to achieve an improved rhGH product.
Implantable silk composite microneedles for programmable vaccine release kinetics and enhanced immunogenicity in transcutaneous immunization.
DeMuth Peter C,Min Younjin,Irvine Darrell J,Hammond Paula T
Advanced healthcare materials
Microneedle vaccines mimic several aspects of cutaneous pathogen invasion by targeting antigen to skin-resident dendritic cells and triggering local inflammatory responses in the skin, which are correlated with enhanced immune responses. Here, we tested whether control over vaccine delivery kinetics can enhance immunity through further mimicry of kinetic profiles present during natural acute infections. An approach for the fabrication of silk/poly(acrylic acid) (PAA) composite microneedles composed of a silk tip supported on a PAA base is reported. On brief application of microneedle patches to skin, the PAA bases rapidly dissolved to deliver a protein subunit vaccine bolus, while also implanting persistent silk hydrogel depots into the skin for a low-level sustained cutaneous vaccine release over 1-2 weeks. Use of this platform to deliver a model whole-protein vaccine with optimized release kinetics resulted in >10-fold increases in antigen-specific T-cell and humoral immune responses relative to traditional parenteral needle-based immunization.
Use of radiofrequency in cosmetic dermatology: focus on nonablative treatment of acne scars.
Simmons Brian J,Griffith Robert D,Falto-Aizpurua Leyre A,Nouri Keyvan
Clinical, cosmetic and investigational dermatology
Acne is a common affliction among many teens and some adults that usually resolves over time. However, the severe sequela of acne scarring can lead to long-term psychological and psychiatric problems. There exists a multitude of modalities to treat acne scars such as more invasive surgical techniques, subcision, chemical peels, ablative lasers, fractional lasers, etc. A more recent technique for the treatment of acne scars is nonablative radiofrequency (RF) that works by passing a current through the dermis at a preset depth to produce small thermal wounds in the dermis which, in turn, stimulates dermal remodeling to produce new collagen and soften scar defects. This review article demonstrates that out of all RF modalities, microneedle bipolar RF and fractional bipolar RF treatments offers the best results for acne scarring. An improvement of 25%-75% can be expected after three to four treatment sessions using one to two passes per session. Treatment results are optimal approximately 3 months after final treatment. Common side effects can include transient pain, erythema, and scabbing. Further studies are needed to determine what RF treatment modalities work best for specific scar subtypes, so that further optimization of RF treatments for acne scars can be determined.